I understand this completely, but your points assume that the quality is in line with other signature restaurants. My contention is that Le Cellier was not in line with these restaurants the last time I ate there (besides price, thanks to the recent increase).
I did read yesterday on the Disney Parks Blog that there are supposed changes coming to Le Cellier that may make it Signature caliber, but as with anything on the Parks Blog, there's a lot of fluff, so I will reserve judgment until I actually hear back from real people concerning the differences. The only things I can judge myself right now are the changes that objectively, without a doubt, occurred: the prices increased and the restaurant now requires two credits on the DDP.
You can put lipstick on a pig, but that doesn't change the fact that it's still a pig. (Not that Le Cellier is a pig by any means, but you get the idea.)
I will gladly eat crow if it turns out that Le Cellier's dinner suddenly has increased precipitously in quality. My bet is that the only things that have increased precipitously are prices and Disney's marketing of the restaurant as in a higher tier than it actually is.