While I may or may not agree with you - the bigger question is, "what else is there to do"? And the answer, for us end-game players, is "nothing".

So, given the choice between farming more food and farming for the low chance of improving one of my existing champs, the answer seems pretty obvious.

That pretty much sums it up indeed. I can't speak for plarium , but I believe this is not the definitive version of this content, and hopefully it will be tweaked in the future. 

Yeah but why?  The whole (imo) idea is twisted, it allows champs, some who are already seriously over powered with empowerment to become unbeatable - so why?  if you're end game you've 'won' why do you want your champs getting stronger?  Some lucky ftp/small spenders - early/mid gamers will get a soul that gives one of their guys abilities a mid/early gamer shouldn't have.  I think Raid has kept it's appeal because whilst the whales can shortcut the process most of it's playerbase follows the same path, this allows for the placing of power at stages of the game where it shouldn't be

I'm endgame, but I want my champs stronger to spend less time in Hydra. I need them to be stronger to more effectively compete in G3 and G4 area. I need them to be stronger to compete in Plat.

I also don't mind reducing the time my solo farmers spend in the dungeons, nor speeding up my weaker FW21 times.