What exactly is the difference between high level play in fourth edition not being very compelling, and high level play in third edition not being very compelling?
I think the problem is that it's high level play, nothing system specific.
I think the real issue here (and yes, its edition neutral) is the time commitment element. A lot of gamers, myself included, love coming up with new characters, dabbling with builds and ideas, etc. The problem for most of us though is that we really don't get a whole lot of time to actually try out these characters due to the time commitments involved in a campaign and the rest of our lives.
As has been noted, it takes most groups years to reach Epic tier. The campaign I'm currently running has been going for a little over two years now and the PCs are only 14th level (we play every other week for about 4 hours, miss a number of sessions for a variety of reasons). By the time I add in work and family and other interests, I really only have time to be in one other game (where I'm a player). That game has also been going for about a year now and we are currently 6th level (again not playing real often, but still).
The problem this creates is that it becomes a major commitment to devote oneself to going all the way to 30th level. That is a really long time to play just one character -- particularly if you don't have the time to be in more than just one or two games. I love my rune priest, but there are also at least a dozen other characters that I would love to play as well. So what often happens is that the players simply burn out on playing that same character over and over again (even with the character leveling up and getting new abilities).
So yeah, I don't think its so much that groups want ways to bring goblins into the higher levels of play (there are already ways of doing that). Rather, its more that they want to bring their other PCs into the game. Unfortunately though, starting out a character at a higher level can be problematic because of the complexity of higher level characters. It takes a while for a player to learn how this higher level PC actually plays. 1st level PCs are fairly straightforward and adding a little bit each level is also pretty straightforward.
So yeah, I think [MENTION=22424]delericho[/MENTION] might be onto something with capping the number of powers at a lower number and simply having them modified by level (sort of like some of the theme powers from Dark Sun and Dragon). Doing this would make it easier to break a long campaign into a series of mini campaigns that start out at the level the previous one left off. So maybe you take your 30 level campaign and break it into 3 ten level campaigns with the players being allowed to switch characters every ten levels (if they want). Obviously, the DM would be free to ignore this idea but the idea would be that its possible to allow players to scratch that itch without it being too difficult. In other words (since I'm still in a pre-coffee ramble) make higher level PCs simpler and you make it easier to start a new PC at high level. This may very well in turn increase the appeal of Epic Tier, which then makes Epic Tier more profitable for WotC, which then means more support and thus more interest, etc., etc.