Greg Costikyan of Manifesto Games (a venture started with my fellow Alliterate Johnny Wilson) posted a column about how the budgets of computer games have grown to the point that publisher can no longer afford to experiment much anymore. You could take his points and apply them to tabletop games almost verbatim. His closing says it best:
I don’t mean to suggest that there is any dishonor in taking an existing game style, and implementing it well; but if the field is to retain its vitality, we need to devise new gameplay, not just new games. This is, perhaps, the real promise of independent games–that, like independent music and film, it can provide an avenue for creativity and exploration, at lower risk than the larger market, and thereby serve to reinvigorate the mainstream.