Level 30 radroaches are idiotic. There's a reason 9 out of 10 people that played Oblivion installed overhaul mods.
Oblivions problem wasn't that everything scaled, it was that the
spawns scaled.
Of all the creatures in Oblivion, I believe only Ogres, Minotaur Lords, Brown Bears, Lichs, Storm Atronachs, a specific type of Daedra and one of the end-game ghosts scaled with the player. Everything else had a level cap. For example, maybe wolves would get stronger up until level 7, Mountain Lions until 16, normal Minotaurs until 22. I'm 100% sure on this because I remember Daedroth getting easier and easier whereas Ogres were turning into absolute beasts as I leveled, even though Daedroth appear later than Ogres.
The problem was simply that when you first played the game, a specific spawn point would spawn a wolf, and as you leveled, wolves became an endangered species, whereas ogres were practically an 11th race in Cyrodiil. New Vegas wouldn't have this problem as it's spawn points are set in regards to what creature spawns there.
Having said that, I'm sure we all agree that Deathclaws, Yao Guai, Fire Geckos, Super Mutants, some forms of ghouls, some specific people and Cazadors deserve to scale with the player whereas molerats should stay where they are. The main problem with the increased level cap is that the Courier gets more HP and more perks, though his damage stays relatively the same. Having said that, they should aim to increase the health of those enemies SLIGHTLY. We don't need Fallout 3 bullet sponges. Say if deathclaws had 300 HP at level 30, then give them 450 at level 50, unless they plan on giving us ridiculously powerful new weapons. What should definitely increase though is their damage. The difference between level 30 and level 50 is 100 HP, and the Courier gets more dangerous perks. This means the deathclaw needs to be as dangerous as the Courier himself if the fight is to stay interesting. If the deathclaw only gets a massive boost in HP and a modest boost in damage (this is the mistake Fallout 3 made), then all they've succeeded in doing is making enemies incredibly aggrivating to fight. That's not interesting: that's a long boring fight that you know you'll win from the start. If a deathclaw was hitting for 120 damage at level 30, then raise it up to 180-200 at level 50. May not sound like much, but that'd mean the Courier tanks 3 less hits from a deatchlaw on normal mode and only an incredibly durable Courier can tank 2 hits on very hard.