I originally started this line of thought while commenting on a BBB post. After reading some further remarks, I realize I have more to say.
Short story is this: WoW is, in my opinion, the best mmorpg out there. Hands down, end of story. This, of course, doesn't mean that blizzard always has it right and everyone else has it wrong. Usually, even the poorly executed games have a gem or two. Such is the case with Final Fantasy XI.
Because of low server population, FFXI allows for high level players to group with low level players by "tuning down" the high level player. This means that their gear and level are decreased to a point that they are comparable in level to the player they are grouped with. In their execution, I think Square didn't do that great of a job, but the concept is something I think Blizz could work with. Here's how...
First, let me preface this whole notion as a "going forward" plan. Until Cataclysm, the damage has been done. I'm only going to use current tier numbers as points of reference which of course would be adjusted to reflect future content.
The main argument behind offering T9 badges for running heroics is to allow new players to gear up and do endgame content. The whole "why make this awesome raid dungeon that only a few people will ever see" argument. I get that. No one wants to spend all that time for nothing. The problem is that people skip over some really great content. What incentive, other than an achievement, is there for someone to do Kara or TK or MC (especially before level 80)? Most people rush past all of these dungeons just to get to endgame. I don't really blame them, and Blizz shouldn't stop them. People should be able to play the game how they want. The question becomes: how do you get someone to run these lower level dungeons and raids without forcing them to do it? The easiest answer is incentives (emblems).
At the moment, badges are just too easy to get. A new 80 can have full T9s without ever raiding. Seems a little silly if you ask me. Why not encourage them to go back to some of that old content that they skipped to earn those badges? Enter "tuning down".
You hit level 80, you join "random raid". You pop into MC at level 63 (yeah, 63, why should you have to be only 60?) with gear that has been tuned down to the correct level. Other 80s might be in there at 63 or there might be an actual level 60. As you kill bosses, you get T9 emblems (level 60s get gear drops). Blizz could even make it so bosses load 3 emblems, who knows? At the end, you get 5 (or more) T10 emblems. This is a system that benefits level 80s who haven't experienced old content and level 60s who don't feel the need to rush to level 80. It also benefits the poor guys who spent countless hours working on a raid dungeon that no one ever goes to anymore.
This same concept can be carried over to regular daily dungeons except you'd earn T8 emblems for bosses and T9 for completion. And for just running a heroic, you'd earn T7s. Each raid you ran, the bosses would give the corresponding emblem (naxx=T7, uld=T8, ToC=T9, ICC=T10). Of course, if you got one of these raids through random queue, your gear would be tuned down and you'd earn emblems as described above. And new 80s have someone to raid with in naxx and os, etc.
Obviously, this wouldn't work now, but after the expansion and with further expansions, why not? So you don't get to endgame content at level 85? When Blizz ups the level cap to 90 with the following expansion, you get to see that level 85 endgame content as a level 90... err, 85/86?
It's not perfect, but I think it's better than what we've got now.