To me it all depends on the nature of the game in question. With long established franchises like Final Fantasy, their recent 'innovations' have deviated too far from the core mechanics long term fans associate with the overall experience, and the end result is that the last few games are pretty much universally despised. If Final Fantasy 13 hadn't had the Final Fantasy label, it would probably have skirted by as an interesting experiment by a new IP that had a few good points but failed overall. The moment they put the Final Fantasy brand on it, much like with the Spirits Within movie, expectations went through the roof and it failed to live up to its legacy.
So what I would suggest is that if developers want to try new things, do it with new IPs. If it works, you have a brand new franchise on your hands and can fold the successful elements back into your main series. If it doesn't, then you may have made a bad game, but you didn't besmirch the name of a long standing franchise doing it. Imagine if Nintendo wanted to get away from the kiddy image they're pretty much doomed to have for all time now. They're not about to give Mario an assault rifle. They'd try it out on something innocuous, and only if it made them a truckload of money would you see Mario finding an uzi in those power blocks instead of a fire flower.
The obvious flaw in this is that a lot of games, Like FF13, sell on the strength of the brand. While it may not be the most loved Final Fantasy (no matter how many confusing as fuck sequels they push out to force it down our throats) it must have made a decent amount of money from day one sales of people, myself included, rabid for the new Final Fantasy game. They'd likely lose some money from the lack of brand recognition, but on the other hand they'd not lose so much money overall I think because in my experience gamers will forgive flaws in new IPs just starting out and still give a tentative recommendation, whereas the standards are infinitely higher in well established franchises and anything short of absolute perfection is considered heresy.
Of course this isn't a universal rule. Try anything innovative in Sonic games and it's considered a pointless gimmick because the fans have pretty much decided that Sonic was perfect on the Mega Drive and any change otherwise is just stupid.
I will say for the record though that I think gaming as a whole could use an infusion of fresh ideas. I can't be the only one sick to death of the paint-by-numbers quick buck yearly FPS parade that clutters up the modern market. It's all starting to feel a little stale. It's been quite a while since I've seen a trailer for a game that made me paw at my monitor like a cat trying to catch a mouse on the television. I remember seeing an early advert for Ocarina of Time and it was all I could talk about for months. These days the big titles are largely just the latest sequels. New CoD, new Battlefield, new Assassin's Creed, new FIFA, blah blah blah. It's not completely hopeless yet, there are still great games. But nothing's dropped my jaw for a long time if I'm honest.