I had a TT (18 ft) for about 3 years before I bought my class C (21 ft). For me, your negative list (while true) wasn't really applicable for me.
1. I normally dry camp, so I can easily just drive out and back. The couple times a year I use hookups, it's for an RV rally, so I'm not going anywhere - and if I were, I only hook up the electrical, so I just pull one plug and I'm out.
2. Going from the 18 ft TT to the 21 ft C gives me about the same living space. But I'm 16 feet shorter on the road.
3. Yep. But, for the extra money, I have a second vehicle that I can use if my regular vehicle is in the shop, etc. I bought used, so the difference wasn't big bucks.
4. With the C, I have the cabover bunk, the dinette and the couch. As I sleep in the cabover, I always have a dinette and couch without taking down the bed. With the TT, I had a dinette and a couch. I slept on the couch, so I had to take down the bed to use it as a couch.
5. Again, I drive around in the C. I don't landscape my campsites. A couple chairs and maybe a sun shade and that's about it. I've fine tuned my gear so that overflow into living space is at a bare minimum. I don't have to spend hours trying to fit all my stuff back into the RV.
Backing up is quicker in the class C also and people don't feel the need to "help". That always drove me nuts with the TT. I have a long narrow driveway and I never had a problem backing the TT into it. But, it never failed some Friendly Joe would be driving through, see me backing up, pull over, jump out and start directing me and I'd end up all messed up. By myself, I'd be backed in and parked within 60 seconds.
For me, I got the RV to go camping and cater to my photography hobby - I wanted to be able to go take photos in the morning, relax while the sun was high in the sky, and then go take photos around sunset. The C is perfect for this type of shooting - the TT worked for the camping, but couldn't succeed with the latter.