I don't know why you guys are moaning about base defense missions. I personally find base defense missions are most fun part in the game.
First, you need to design your base smartly...
A lot of people know all that and still dislike base defense missions, probably because they get stale really fast when the aliens send one battleship after the other. But this thread is more dedicated to peoples' dislike of weak base defense facilities (laser and missile defense) because there's no use for them in the game.
Also, there have been some updates to base defense facility code since this discussion took place in 2015 and some in 2017:
* Base facilities can now launch projectiles onto the geoscape, and aliens can spawn projectiles onto the geoscape which can hit player bases and damage or destroy facilities.
Tech Comm * Base facilities can cost any type of item to build, and can refund some or all of that item (or other items) when they are removed. (buildCostItems)
* A global variable can be set which will make UFOs drop less aliens based on their remaining hit points. (lessAliensDuringBaseDefense: true)
Ruleset Reference Nightly (OpenXcom)Keep in mind all of these are options for mods, and none of them affect the unmodded game.