The fact that 5 things I used the most in previous games are removed - Unarmed (I don't call it H2H since this one makes more sense), Unarmored, Athletics, Acrobatics, Block (you can't use it in unarmed combat, so for me it's gone).
Since when has Block ever been part of Hand-To-Hand?
Daggerfall? Shields were just Armor Bonus, no Block skill at all.
Morrowind? Block required a Shield, which went away when you raised your hands to fight with your fists.
Oblivion? Blocking didn't reduce incoming damage, and only staggered enemies if you were a Journeyman in Block.