> * Way too easy to quit the whole browser with Ctrl+Q (Chrome uses Ctrl+Shift+Q)
Saying that it's nitpicky to include this in your list would be huge understatement, it's straight out ridiculous. I have always found Firefox to be more responsive and less resource heavy than Chrome, so I don't know why you had problems with that.
But yes, you are right when you imply that Firefox seems to have prioritization problems, lots of them imo. However, it is understandable to me, making the UI looking prettier is for marketing, not usability. Most of these things you listed are not addressing a lot of users, on the other hand, having a flashier UI would address and (potentially) attract more users. But their management still needs to improve, and as a company, they should have better direction.