Yesterday's question was somewhat leading, because I knew some people would reply with "there are no pure raiding games because people only raid for the gear". Which I don't think is true, I'd even say it *cannot* be true. Because the gear you get from raiding is only good for raiding, if you don't raid there is absolutely no need for the stuff: You can't use raid gear for PvP because it doesn't have resilience, and you don't need it for daily quests or heroic dungeons, because it is overpowered for that. So somehow players must find raiding inherently fun. Which makes it interesting to see how the fun changes when the basic rules of raiding change.
Blizzard just announced their vision of raiding in Cataclysm, and Spinks doesn't like it. She of course is totally correct in stating that a regular 25-man raid is logistically harder to organize than a 10-man raid. I don't agree with her assumption that a 25-man raid is also inherently more difficult; she says "25 people have to execute the fight correctly, as opposed to just 10", which just isn't true. If you did 40-man raids in vanilla WoW you know that depending on the encounter only 25 to 35 people in the raid needed to execute the fight correctly, while the rest could be tourists. Which had its own advantages for teaching new guild members how to raid. So if Blizzard, as they say, make 25-man raids as easy as 10-man raids, the larger number of people means that a few overperformers will again make a few underperformers possible, which unless your name is Gevlon is a good thing. Any restriction to group content where all participants need to be at exactly the same power and skill level makes organizing more difficult and causes problems of social cohesion.
So I would think that for guilds that *can* get 25 people together, it will be in Cataclysm even more advantageous to actually do so, because if it works like advertised, the 25-man raid will give more item drops per player, at identical difficulty level. The alternative of running 2 or 3 10-man raids in big guilds is far trickier, as there is a very real risk of an A-Team and a B-Team forming which progress at different speeds and end up splitting the guild.
It is quite possible that this announcement of changes to raiding is actually of far lesser consequence than the changes to the speed of raiding which were hinted at in various class announcements. Supposedly raiding in Cataclysm will be somewhat less button mashing twitchy, and give somewhat more opportunity to play your class well. Larger health pools compared to incoming damage and outgoing heals will result in less "lets spam the fastest heal all the time" healing, especially since mana efficiency will also make a comeback. I'm not sure if the average raider nowadays is actually able to play his class really well, or whether the last two expansions just taught him fast reaction skills without having to spend much thought on what button would be best to hit. If raiding goes back to be more similar to raiding in vanilla WoW, some people are in for a surprise, because with just the set of twitch skills they acquired in WotLK raiding they wouldn't have gotten past Razorgore. If Cataclysm raiding turns out to be like the devs said, I'm looking forward to it.