As to fillet and valet, they joined english before the contemporary french pronunciation, and are much closer to the middle-french.
My favorite is probably crepe, which Americans pronounce like an almost diphthong-y craype (or crape like grape I guess) when crep (like step) would do just fine and be closer to the original.
But as a native French and basically-native American speaker, I also couldn't really care less about it, or about things like Americans pronouncing the t in croissant, or French people being unable to say the.
I say it the American way when I speak English anyway because that's just how it is. :)
See also: Cairo, IL or Versailles, KY...
Fontainebleau State Park -> Fountain Blue State Park
These were two off the ones that really stood out from my travels.
It's not always that way though, consider 'niche': it's AmE that decided it's 'nitch'!
If there were just French words pronounced in a French way and English words which came from French and are now pronounced in an English way that would be bad enough but in fact we have a whole spectrum of bastardisation.
Fillet/valet are mis-pronounced because of mallet, pallet, etc. Renaissance? Nail, snail, tail, etc.
It really is that simple, we're just pronouncing them as if they were an English word.