To answer the two questions in your final sentence above: Yes, they can stay looking good, and they are difficult to maintain. The level of difficulty depends to a great degree on the variety, with HTs being the most difficult.

Pruning regularly is a vital part of rose tree culture -- to avoid that lop-sided look, for sure, but most importantly, to ensure greater stability by evenly distributing the weight of the scion over the graft.

IMO, all grafted trees (& probably 99.9% are grafted) should remain staked. Some gardeners think that stakes are important not only for support, but should be placed so as to protect the trunk from direct sunlight during the hottest part of the day.

I think you're right about HTs being the poorest subjects for tree roses. However, among the most beautiful ones I've seen were two 'Medallion' trees that flanked the door to a greenhouse at a local nursery (since closed). Ofcourse those 2 received constant care by professionals and optimal winter protection.

My personal favorites are 'weeping' standards using heavy blooming varieties with small flowers. 'The Fairy' and 'Danae' are Polyanthas that work well. Some of the trailing 'ground cover' varieties would also be good subjects. Whatever the variety, though, they require lots of attention, TLC and a protected site if you live where high winds are likely.