By coupling status effects to defenses, 4e has made it so it doesn't matter what damage is connected to the attack, the defenses still need to scale somehow.
While I can agree to an extent, you're also leaving out resistances. Sure, they're a bit more varied, but fire, necrotic and even poison come up quite a bit. As an example: Last Saturday's paragon adventure. It was scaled for a 13-14th level party and my Swordmage was at 11, with two 12s and 2 13s. Incline leading to bridge, leading to frontline defending BBEG Necromancer flanked wide by two artillery.
I win initiative, double move, Armathor's Step to the balcony with an action point and mark the Necromancer while in his face. He teleports out and crits me for 40 Necrotic + 10 Ongoing Necrotic. And I failed the Ongoing Necrotic save for three rounds but I negated his best regular attack and made him change. Also, a beefed up Boneclaw moved between us after squeezing up the stairs (I had been imobilized for two rounds after failing that save too but the Necromancer was out a couple of rounds then due to a Sleep spell from the Orb Wizard).
I had initiative, I hit the Boneclaw with my Voidcrystal Longsword and next round placed him safely back on teh lower level three squares diagonal.
I took only 30 of 70 damage which negated more than an actual hit would, didn't take numerous attacks that could hit me fairly reliably (even with a 32 AC) because I displaced the Boneclaw.
These things exist outside of the raw math.