I think both sides are right, ie, the side arguing the pinkness comes from the feed and the side that argues it's genetic.
In Brook trout it's definately genetic and of many brook trout I've eaten over the years the only ones I ever found with whitish or very light pink meat were spawners in poor condition. I've fished them in lakes where the primary foodsource was leeches and other lakes where it's scuds and others where it's chiornomids and the meat is still always Pink.

In Lahontin cutts it seems to me that only Maiden fish (pre spawn) that have been feeding heavily on scuds ever develope any pinkness or flavorfull meat. The larger fish will be white meated and bland tasting regardless of what their feeding on and most of the smaller ones are too.

Among the salmon group it's even more confusing. In Alaska the" Pink" Salmon by the time they return to the vicinity of their stream are not very "Pink" anymore and taste very bland, whereas most of those occasionally caught at sea are quite pink and tasty.
The Chinook salmon exhibits both types Pink/rich and white/bland whether at sea or at stream mouth ready to spawn in a quite confusing manner.

As for the F&G practice of adding pigment to the feed to make our trout a more desireable slab of pink meat, I can only say this is stupidity and waste to the highest degree and supports my argument that F&G supports and encourages a "meat fishing" mentality at the expense of the SPORT fishing is supposed to be.
Now get out there and stock up that freezer guys. They'll turn back to white by next year.