Agreed... while the Remaster looks good, it's pulled down by the abysmal performance. This in itself is a dealbreaker for many people, including me. Furthermore the gameplay system under the hood is 95% the same as the 20 year old oblivion, with all the same flaws, while Skyblivion will have all the gameplay enhancements from Skyrim. This just sucks.
I also think, that if all new models, textures, vegetation from the official Remaster were used in the original Skyrim Engine, the game wouldn't look much worse. And it would run on every computer. Looking at how modders improved Skyrim graphics - making it look like a next-gen-game - it didn't need the UE5 graphics pipeline for that.
Skyblivion will most likely be the better game. The biggest problem with Skyblivion however is, that it will not be a standalone game. Bethesda should allow it to be a standalone game - like the "Half-Life Black Mesa" - so that the install process would be simple for the people.