Stuff from dead operatives is correctly recovered after the mission... unless it's destroyed by explosions.
As for the requested reorder functionality, it only creates questions and problems:
1. what if you don't have enough storage space?
2. what if you don't have enough money?
3. what if you can't buy it, but need to manufacture it?
4. what if you need to manufacture, but don't have enough money?
5. what if you need to manufacture, but don't have enough manufacturing space?
6. what if you need to manufacture, but don't have enough special resources?
7. what if you cannot buy or manufacture it at all (e.g. can only use scavenged stuff)?
8. With OXCE, there would be even more questions about various pre-requisites...
Pro tip:
...buy and manufacture ammo and other consumable stuff periodically so that you always have enough for at least 2-3 missions. If you play well, you should never see a screen telling you you've run out of ammo...
Pro tip 2:
... don't EVER put everything on the craft... because you will always get the message (and can potentially lose a lot of stuff in an explosion)