I completely agree with everything you said, but I also have to admit that even after beating BB and DS3, I'm still very bad at these types of games, so bosses that for me are difficult may be very easy for more skilled players.
(I also did Romina before Messmer since I was randomly walking around until I stumbled across her arena.)

I hated the absurd coverage (both in distance and defense) that Romina had, but as bosses go, I think the worst one by far was Commander Gaius because that charge hitbox/damage is just all over the place, making the fight feel more like one where luck is a factor versus skill.

Agreed 100% on the map, especially when you visit the Suppression Pillar and get a chance to look around at the world or see places that seem nearby but require very circuitous routing to get to them. The legacy dungeons were very okay, but the trips to those places were definitely far more interesting (although the lack of signposting even with the Sites of Grace made finding some of them a pain...this is probably my fault for doing Romina before Messmer, though).

I think that the alterations you spoke on explain why despite looking forward to getting this remake/master/whatever for years, when I finally acquired it on PSN, I never finished it, but still managed to find the time to grab mods for other Soulslike games to take trips back into them again. There was a distinct feeling that something just wasn't right when I tried to run through this version and I couldn't bring myself to keep going, despite absolutely loving this type of game and the original version of it.