Participation for Epics may be down a bit, but I think we need to keep in mind it was never that high to begin with. While I'd love to see dozens of reports for each game too, the Epics have never been about catering to a large group and they never will be. That's not to say we're a bunch of elitists here (at least I hope not), but at the same time the games aren't designed to cater to a mass audience either. We're never going to see the kind of participation that the GOTM receives, partly because we play such high-difficulty games and partly because the reports really are a lot of work to do, probably more than a lot of people are willing to take the time to do.
As far as reports go, everyone simply has their own style of writing, and that's something that can't be changed. Sirian and I happen to write rather similarly, partly by coincidence and partly due to the fact that I unconsciously modeled my first reports after the ones he had on his site. But we all write differently, from Charis at one end of the spectrum who takes perhaps the most fictionalized approach to T-Hawk's more clinical dissections of how to take apart the game and win. I'd contend that the different way in which we all write is part of what makes reading the different reports so interesting.
If participation is going down, I'm sure it's due to what the others have pointed out: declining interest in Civ3 and lack of time for the reports. Civ3 has been out for over a year and a half now, and that's a fairly good life for most PC games. You can only play so many games before becoming tired of it, after all. We also need to keep in mind that work that goes into the reports too; I've said before it's a labor of love, but at times it can be more like just labor. It's a doubled-edged sword when it comes to the reports; the better they are, the fewer games you get to play. It's the very fact that I won't play a game unless I can do a first-rate report on it which has kept me from playing more Epics. I simply don't have the time to do both. If you look on my page, you'll see I've almost never played Epics back to back; that's not an accident, but a reflection of the time which goes into each one. When I did play several games in close proximity, I either had to cut the reports short (Epic24) or nearly killed myself trying to get them done (Epic18). Neither one of those is a good situation.
So I can only ever play perhaps one out of every two or three Epics. Would it be better to play more games and sacrifice report quality? I don't know the answer to that question. All I'm trying to do is throw this out there so you have a better idea of what I'm thinking and why I'm absent in a lot of games.
It's all worth it for the good games (and Epic27 was a VERY good game) but they do take their toll. The Epic27 report took about 15 hours to do, on top of a long game before that. I've only got so much time too; I have three different research projects lined up for this summer as well as spending a month abroad studying at Oxford in July. In other words, I won't be able to play more than a handful of games this summer. I'm sure everyone else is in a like situation, and there's no reason to bemoan this fact. As long as we can still get 5-10 people routinely for each game, there's no reason not to keep running Epics.
I've rambled a bit of course here, but I hope I gave some indication of my thoughts. It's no one's fault that participation is down a bit, and we really shouldn't worry too much since we almost never got more than a dozen people even in the largest contests.