I never said this, so please don't words into my mouth that I didn't said.
What I did said is: the more you add, the less you start getting in return after a certain point, a.k.a. "The law of diminishing returns (https://en.wikipedia.org/wiki/Diminishing_returns)"
That was just a quick way to summarize your "diminishing return" idea. Over-investing in something with a diminishing return is a bad idea, you claimed that some mods do that and presumably you think that's why they need this feature (otherwise why mention it here?) It isn't true any ways: even a mod that adds a single mission somewhere in its development time could use this feature: It would allow people who are following the mod's development to not have to play in their save to see that one new mission, in exactly the same way it allows Piratez players to see the one new mission. Number of previous missions has no impact on how useful this feature is at a given point, but makes this feature increasingly useful as more missions are added, because it saves more and more save editions.
It was an aside prompted by your double post, so I'll spoiler my reply to the idea that "more missions is diminishing returns" since I don't think it's really relevant.
Your claim that after a certain number of missions you are not getting the same value out of them is true, but that's not a bad thing and you are not getting less necessarily. Instead of getting "more different within one play-through" by having a new mission in a small subset, you get "more variability between different play-throughs" because there are more possibilities for the RNG to generate.
Not everybody want to see everything in one play-through, although I respect that that is how you seem to think (wanting to optimize terrain apparition so they are all sampled in a campaign, same for special missions). If you want to replay mods, more missions makes sense so you can get variations on campaign scale. So I would not call it a diminishing return: You get more enjoyment-length than otherwise. If everything is featured in one campaign, then yes, you do get diminishing returns because the mod was already special. It's just a bit more special (one more mission) but since I've already seen all of it, I still not going to play it twice. But not all mods are designed so you see everything in one go.
And I finish quoting myself by saying that so far I haven't seen a valid reason for this change. Some people sure 'want' this, but to me there's no need for it since it isn't needed for testing or generating specific missions (there are already better ways to do it)
It was mentioned already: Adding the possibility of new missions to the table as soon as the upgrade comes up so that you:
1 - make it possible to see new content (as generated by the RNG instead of cheating it in your save)
2 - increase your odds of this play-through being different from the previous one by adding the possibility of new missions.
Some people are dedicated enough to wait for the RNG to generate the mission they need/want to see and consider save editing to tweak/pick alien missions cheating. I am one of those. I want the computer to play the aliens. I don't want to look at what is generated and want even less to put something there myself. The only part I can tolerate tweaking is adding possible missions because there is no other way to see Dioxine's work and, as you can see, I am trying to get away from even that part of save tweaking. I will never add/remove/change ongoing missions (although I can understand the value of that for LP's, like Meridian's FMP LP, since you want to maximize content/time for your watchers)
What I don't understand is why you seem so opposed to the idea. You have nothing to lose, others have something to gain, what's wrong with it? Devs are the only ones to lose something from working on this (their time) and I'm sure they can figure out where to spend it by themselves.
I was talking about specific information of what changed, like this:
alienStrategy:
possibleMissions:
- region: STR_NORTH_AMERICA
missions:
Nothing changed
- region: STR_ARCTIC:
missions:
STR_MISSION_LOC_RET_BASE: 25
- region: STR_ANTARCTICA
missions:
STR_MISSION_LOC_RET_BASE: 25
- region: STR_SOUTH_AMERICA
missions:
STR_MISSION_LOC_RET_BASE: 60
- region: STR_EUROPE
missions:
STR_MISSION_LOC_RET_BASE: 60
- region: STR_NORTH_AFRICA
missions:
STR_MISSION_LOC_RET_BASE: 60
- region: STR_SOUTHERN_AFRICA
missions:
STR_MISSION_LOC_RET_BASE: 60
STR_MISSION_RETICULAN_TRADING: 100
STR_MISSION_RETICULAN_TRADING: 110
- region: STR_CENTRAL_ASIA
missions:
STR_MISSION_LOC_RET_BASE: 60
STR_MISSION_RETICULAN_TRADING: 60
STR_MISSION_RETICULAN_TRADING: 70
- region: STR_SOUTH_EAST_ASIA
missions:
STR_MISSION_LOC_RET_BASE: 60
STR_MISSION_RETICULAN_TRADING: 60
STR_MISSION_RETICULAN_TRADING: 70
- region: STR_SIBERIA
missions:
STR_MISSION_RETICULAN_TRADING: 50
STR_MISSION_RETICULAN_TRADING: 70
- region: STR_AUSTRALASIA
missions:
STR_MISSION_LOC_RET_BASE: 60
STR_MISSION_RETICULAN_TRADING: 50
STR_MISSION_RETICULAN_TRADING: 70
- region: STR_PACIFIC
missions:
STR_MISSION_LOC_RET_BASE: 60
Not just a "New mission type: this". Most people, when seeing that, will think "Cool! I can see a new mission once I update" and not know that they actually cannot generate that mission since they'd need to find and write a whole bunch of stuff in their saves that they don't know how to find/write.
Also, there is no reason to remove perfectly fine code that can handle old save, so there is no reason why this would break saves. If there's "possibleMissions" in the save, read it the old way, if there's "completedMissions", read it the new way. It is an investment of dev time, of course, and that's why it's a suggestion, not a demand. They are free to determine how they want to spend that time and I don't think we have to worry about that.
BUT you need to cut this by the factor of at least 6 to see a mission, since most missions can be generated 5 or more times (once for each allowed region), so there's a good chance to see all missions in 3-year campain,
That doesn't help in seeing new missions, since they never got a possibility to get into the generation table. You have to wait 11 game years for Piratez to generate a reticulan mission if you upgrade now and don't tweak your save, because you have to wait until you ran out of all other missions for it to generate again. Then it should take only about 3 game years to see them ;)
PLUS it is definitely my intention that some people won't see some missions during a single playthrough
Well, with the amount of content you already have, it's a good thing we don't need to see it all to finish ;) Waiting for the next playthrough can work too, but having the missions integrated in the current one makes it likely that it will be more novel compared to the previous, which is a plus.
Personally, I'd prefer a third option: a simple switch that tells the game to ignore 'available missions' and always choose at random (using mission/regionWeights) from the ruleset file.
An interesting alternative option, which would be easy to implement before "completedMission" since that would involve generating a whole list every load. "completedMissions" can then be built upon that, by removing what is listed in the save from the generated list.