Miss chance is better, sure. But AC still is useful at later levels. My last two mid level characters, reaching levels 10 and 9 before the campaigns ended, both had very good ACs and both were frequently missed by enemies because of it.
In response to the above poster:
Critical hit: Unless the guy rolled well both times, a good AC might have prevented the confirmation roll.
Getting hit multiple times: Yes, this is exactly why AC is worthwhile.
Flatfooted: Actually, the "rogue 4 levels higher" line is ONLY to negate Imp. Uncanny Dodge's flanking protection. Uncanny Dodge's flatfooted protection cann't be overcome, and ninja can't sudden strike on a flank, so I think your DM flubbed things to your detriment there, actually.
Mooks: Did you DR make their bow damage fairly negligible, at least?
You were playing a Barb, a class not known for great defenses (other than sheer toughness) to begin with, and then played it up further by neglecting your AC for offense. I don't think that really proves the uselessness of AC at all.
The 100+ critical hit wouldn't have been confirmed if I had a typical AC for the character level. I was mostly not wearing armour as part of the character's theme (I'm bigger and tougher than all of youse!) rather than any sense of character optimisation. That particular character copped at least 3 100+ crits that I can remember, luckily he had 200+HP (pre-rage)when he was retired...
DR did make the mooks attacks less painful. Still, with 15/20 attacks hitting and doing 1-2 points of damage/hit it adds up pretty quickly. Nobody else was taking damage in that encounter, so I suspect it was just intended to mess my barb around. It was still fun though.
In 2nd edition, armour was just plain better than 3.5 I think. There were fewer drawbacks to wearing it (compared to the monstrous skill check penalties full plate and heavy shield impose in 3.5), though I mostly think this was because DM's back then just made decisions on the fly and on the back of how well you could describe your actions. In 3.0/3.5 there was much more use of a skill check as a "crutch". It was also harder to hit tough AC's. Fighters still gained effectively +1 BAB/level (-1 THAC0/level if you prefer...the change in mechanics makes a discussion harder), but super-high bonuses to hit from strength and magic weapons were almost non-existent. I don't remember what an 18/00 used to give you as a hit bonus, but doubt it was much more than +4. By way of example, my barb that I've discussed had a bonus to hit of +10 from strength when raging (Str 30), plus his bonus from high BAB, plus magic weapon bonuses, plus spell buff bonuses... It wasn't uncommon for him to achieve a first attack of +30, the equivalent in 2nd edition of a THAC0 of -10, which was unheard of!