I'd say: You know very well what you need, so go ahead and create something that fits your needs. You'll end up with a solution for yourself, and I'm pretty sure there are people out there for whom this solution fits too. (Unless, of course, this is primarily about creating and selling a product.)
By the way, despite there being PLENTY of bug trackers out there, most of the people I talk to are not satisfied with the bug tracker they use.
I've noticed this as well. In general, there seem to be some kinds of tools which are very personal. Issue trackers, TODO-lists, notebooks. I'm pretty sure it is impossible to satisfy everyone with a single tool. Everyone wants to optimize it for themselves.
In these cases I think a decent solution would be to make a general backend service and well-defined data format (for interchangeability) but make it easy to add customized (their own or third party) frontends/skins by individual users.
Next time I meet somebody who's unhappy with their bug tracker, I'll ask if customizing it would be an option for them.