I don't think anyone's mentioned that you can get mufflers to kill the exhaust note. Problem solved
Mine was never loud stock, now it gets kinda annoying on long trips. On the streets, I love it. Highway, not so much. But that's solved with turning up the radio 
200K miles bores you? Do a rebuild! Rear end whines? get gears installed correctly (if that's not the problem, I have no idea what you're talking about then)
Can't say much for the interior or available space, but all the other things you mentioned can be changed/upgraded.
No reason to feel guilty about it, we all get there. Even I feel bored at times with mine, and look what I did to it.
Mine was never loud stock, now it gets kinda annoying on long trips. On the streets, I love it. Highway, not so much. But that's solved with turning up the radio 200K miles bores you? Do a rebuild! Rear end whines? get gears installed correctly (if that's not the problem, I have no idea what you're talking about then)
Can't say much for the interior or available space, but all the other things you mentioned can be changed/upgraded.
No reason to feel guilty about it, we all get there. Even I feel bored at times with mine, and look what I did to it.