The concern is not necessarily incorrect - gear rewards have been pretty effective in motivating at least a certain segment of the population - but I believe it to be a misguided approach. Taking that tack pre-supposes that the activity of raiding is so non-fun that it is only viable when propped up with gear rewards, which might be why Blizzard does not find it persuasive.
The role of gear in raiding
Tobold has a skirmish with his commenters in which he argues:
"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."I'm not convinced. At a minimum, PVP weapons are only attainable by top-rated Arena teams, with the explicitly stated design that other players would raid to fill at least that (somewhat crucial) slot. Also, once you have sufficient resilience, access to raid gear gives you the option of swapping in higher DPS items for more damage (a crucial element of WoW's burst-heavy PVP).
More seriously, assuming that raid gear is not needed for daily heroics assumes that players are doing them for the challenge, which is flat out contradicted by the evidence. If players wanted to be challenged in this content, they wouldn't be running it in raid gear up to 100 item levels above what it was designed for, and using gearscore as a criterion to kick out anyone who might actually need the upgrades for fear of slowing down their loot run. The main reason why 5-mans are so popular is PRECISELY because raid gear trivializes the content. Five-man content was on its last legs until Blizzard bribed raiders into trivial content with inappropriately high-quality loot.
Emphasize the positive
If you're out to make the case for the 25-man, the better approach is to emphasize the positives. The posts that I linked up top try to move things in that direction, but the take-home message is always that players will not do larger raids unless they are bribed with better gear. As if that weren't enough, over on Tobold's post, longtime commenter Stabs notes:
As Stabs predicts, Ferrel, who runs a raiding group in EQ2's smaller two-group format, seems to be pleased. This is the second big strike against the larger format, in that it disproportionately rewards the out-of-game logistics required to get a large number of players with the appropriate mix of classes online at the same time.
"You know, I've seen a lot of people lamenting that 25 man raids won't be organised for them but I haven't seen many people who actually do the organising complain."
(Then again, there's nothing about this logic that cannot be applied to even smaller groups - if the prime directive of MMORPG's is to allow players to experience content with their friends, why does that cease to be valid for players with only 5 friends, or players with none at all?)
We live in an era where even the biggest studios cannot produce content quickly enough, and where it is no longer viable for them to set aside the lion's share of the content for a format that few players will experience. Blizzard has concluded that opening the content to more types of players - smaller, and less hardcore groups - is the only way to justify the continued development expense.
In response, the loudest, most consistent counterargument has emphasized negative stereotypes of raiding - that it is an unpleasant loot slot machine that players only do because it allows them access to exclusive storylines and superior gear. If raiding is so bad that this really a big part of the truth (it certainly isn't all of the truth for all of the players), is the format even worth saving?
Blizzard doesn't seem to be convinced, and I'm not sure if I blame them.