You have some points here, but the Bash part is _not_ the problem. Bash is everywhere and the true fix to that bit is to learn Bash: It's not hard and I benefit from my Bash skills everyday, it's one of the best things to invest even a bit in. Just don't write "actual software" in Bash.
I'm pretty proficient in bash myself, and error handling, debugging, decoupling and refactoring in bash are all horrible. It's just not design for being good at a script with more than a couple of lines. The fact we do use it for such purpose does not make it good at it.
The fact it has no namespace, the lack of decent data structures and the very limited functions also all leads to making it a poor foundation to build a lib on. Hence deb packages don't have any kind of framework for basic things: you are on your own.
