I can only speak for myself, but I think the cause is often practical: good things are often baselines that don't need to be changed and can usually be ignored more than the bad things which actually do need to be addressed.
This tends to lead to a very negative outlook, but is more a consequence of pragmatic mental habit than anything.
That said, like everyone else I've noticed that pragmatic negativity doesn't translate well to other parts of life. Switching mindsets from "what's wrong and how does it need to be fixed" to "what's enjoyable" can be quite a leap when you're used to thinking a certain way.
I've got a similar view on the situation - perhaps technical people are trained or enculturated to look out for the things that can be improved/fixed, rather than taking time to celebrate progress and achievement.
This tends to lead to a very negative outlook, but is more a consequence of pragmatic mental habit than anything.
That said, like everyone else I've noticed that pragmatic negativity doesn't translate well to other parts of life. Switching mindsets from "what's wrong and how does it need to be fixed" to "what's enjoyable" can be quite a leap when you're used to thinking a certain way.