@KD, this is not a good argument. The enemy mix at level 1 is the same as the enemy mix at level 30, relatively. If on the average you're fighting enemies with an AC of say 17 at level 1, then it will be 47 at level 30. Sure, there will be one now and then that is higher at either level, and some that will be lower. You're basically fighting enemies from 0 to 5 levels above your own. If you could hit those enemies at level 1 then you'll be relatively -4 vs them at level 30 without expertise, or -1 vs them with expertise.
There's also the now rather common +2 ability score bonus for many EDs. Thus a character taking an expertise feat and any of those EDs has no loss of accuracy at all. In any case why was it necessary to have this expertise bonus when PCs were easily curb stomping every epic monster out there? Sure, it wasn't because the PCs were TOO accurate, but being MORE accurate was needed? Nonsense.
Yes, I mentioned the +2 for ED (but I stated that it was 21st level which wasn't quite accurate).
There's some major differences though between level 1 and level 30:
1) How many times do you face off against a level 4 through 6 foe at level 1?
2) How many times do you face off against a level 4 through 6 foe at level 1 along with an entourage of NPC allies? I don't know of any DM that just throws Tiamat at the group. It's usually Tiamat plus a few extra dragon helpers and a bunch of traps, etc.
3) How about terrain features? At level 1, it's a minor nuisance to encounter a wall or a square of difficult terrain. At level 30, the PCs have to be able to get across a 5 square ravine, even the PCs that have lousy Athletics skill.
4) And monster abilities are so much tougher. Ranged attack monsters flying 40 feet in the air that the defender and leader cannot touch. The DM should run low to mid 30 level monsters with 22 Int as brilliant tacticians. The best he can think of.
5) At level one, most of the monsters are Standard monsters. At level 30, most of the monsters are Elites or Solos.
Sure, if you set up your level 30 encounters like your level 1 encounters, than the PCs will mop up. But by level 30, the encounters should be EPIC in scope. Challenging. Unexpected. With magical effects and traps and allies.
Not, we enter a room and fight the bad guys.
The PCs have a greater number of options and stronger options at level 30. So should the bad guys.
But my personal opinion is that there are a few reasons why players can start to mop up at Epic levels, even without Expertise:
1) The PCs have a lot more options than any given NPC.
2) After playing their PCs for 20+ levels, the players are a lot more familiar with the abilities of their PCs and how they synergize with the other PCs than the DM is familiar with the NPCs that he is using for the very first time.
3) Many DMs do not take out the time to analyze their Epic level NPCs in order to create a challenging encounter. They might throw in some interesting terrain, but a good challenging Epic NPC encounter is not easy to design like a first level encounter. The DM has to look at the synergies of the NPCs and actually take out time to design the encounter. Just throwing a bunch of Epic monsters together doesn't work like it works at level one. Players will pick up on the montser weaknesses and rip them apart if a DM does that. He has to design the encounter to minimize their weaknesses and emphasize the synergies of their strengths.
The reason he has to do this is precisely because of #1 above. The PCs have so many options that they are not using too many At Will powers (except for some Essentials PCs) until the middle of the encounter.
But, I think that you are mistaken. Anecdotal evidence from people who have run the encounters isn't the only thing that one should look at.
If a first level Cleric has +4 to hit the 17 Will (40%) of a 4th level monster and without Expertise, the 30th level Cleric has a +30 to hit the 47 Will (25%) of a 34th level monster, many of those attacks will miss. Sure, every Cleric could be a Divine Oracle, but that's boring.