Well, they do not, because it's just impossible to make everything right for everyone. D
Thing is though is that adding the things we want back in wouldn't displease anyone. You can't really justify not having options in a game like this.
Merged Chest and Greaves? That pisses off people who like to wear different combinations, yes, but in the end they're giving us more armors this time.
Nothing was stopping them adding more armor varieties before. The fact that there are thousands upon thousands of armor mods, a significant portion of which actually fit in with the game extremely well, often seamlessly, proves that it isn't impossible to create great armor sets with separated armor.
And you know what, if the art team wants to create armor sets that somehow require merged armor pieces, then let those armors be merged, and separate everything else that can be. Something like the OB dark brotherhood armor, for instance, would have made no sense whatsoever to be separated. But its easy to see how you could separate iron armor for instance.
Romance and Marriage? People got pissed of because of that, even when it's totally optional.
Problem was that it was a waste on the dev's part. Stuff like that is better left to modders.
Was it fun to level them in Morrowind or Oblivion? NO.
Then the solution is to make them fun to level. Not to remove them. Removal =/= fix.