Meh. It's a freemium game. I don't particularly take issue if you have to spend $ to get the uber (i.e. 3rd for max evolution) version of the unit, as long as it's possible to get a version if you're prepared.

That said, I think they sort of blew it on the evolution. As I understand (haven't done it since only have dupes of 4* or less which aren't "keepers") you need all 3 to evolve at all, so getting only 2 (i.e. what the really prepared but not spender should be rewarded) doesn't really mean anything. Should have been like a first evolution if you get a 2nd, then a second marginally better evolution if you spend for the third.