[..] I know you need some basis to evaluate potential recruits or even pug members. But I do wish there was some way to turn around this virtual phobia of inefficiency -- this terror of being WRONG -- that we have managed to instill in our player base. I honestly think it's one of the greatest challenges facing the game.
Rift is also running straight into this trap at high speed.
So what can we do to fight this challenge?
1) You can make it harder for players to optimize. For example, by disabling the export of combat logs for statistical analysis. Or by disabling combat/dps meters, the armory, inspecting other players, etc. Evidence from MMORPG-history shows that this helps to a degree.
2) You can remove one-dimensional goals. In WoW, a damage dealer is exactly as good as his damage-per-second. Of course, he should also try to interrupt, but in the end everybody looks at the dps meter. That's concrete and readily available feedback. If a damage dealer had to do much more important things than dps during a fight, it were harder to optimize a build. If fights were completely different and not as similar as, for example in WoW, it would also help.
3) You can make content less predictable. A procedurally generated dungeon with or without traps, with or without undead, would make it much more reasonable to take a specalists for traps/undead with you, even though there might not be any such challenges. Of course, this also requires that players can chose to evade some encounters that they just aren't prepared for. This would add a completely new interesting decision to the MMORPG; and a new minigame: information gathering.
4) To make perfectly balanced challenging PvE content, you need to know how many players are going to try to beat it. However, this also leads to every non-optimized player being a problem. Now, in a non-instanced MMORPG, every additional player would help. Players would love to add more players to their groups, because more is better. Of course, this also helps with immerison.
5) And, finally, you can disable any 'interesting decision' that changes the efficiency of the character. If the game offers enough interesting decisions in other domains, this might even be a good solution.
Also have a look at my post last year Cookie Cutter Speccs. I realize that this blog is now old enough that I have written about almost anything more than once already ;)
6) There is a sixth option. You can reduce the challenge of content. The less challenge, the less incentive to optimize.