Re: This is a genuine question to all software devlopers...
> One thing I've never understood is why software is released with known bugs
In addition to the already noted: changes (including bug fixes) often introduce new bugs, there is also the problem that many bugs are benign – no one is affected – and the change adds risk (the new bug could be far worse).
There is also the case where an issue is found late. Should the release be delayed for that fix? (Especially true of test releases.)
Contemporary software systems are very complex. Even a small system will have tens of thousands of interacting parts. Mostly these do not interact (much effort is put into avoiding interactions) but sometimes they need to, and sometimes they do unexpectedly. Any change can potentially trigger an unwanted interaction.