Main issue is no factories are producing parts anymore so anything like that is scavenged and can't be relied on in the long term. Same reason no one has mobile phones anymore (other than the fact there is no internet/phone connection)
Stat decay is something I will look into, but won't promise anything as it is part of the gameplay loop and until I have balanced it properly I don't really want to add something in that prevents me from finding out from players where problems might lie. If people have problems with it, they will sooner just switch it off instead of reporting issues to me so I can fix it.