This is a significant buff that might make them too strong. Also bottleneck issues. Kingdom with no thrashers, Alice gains the two Goats, game over.
That’s why you’d certainly separate the piles if you’re doing it that way. Agree that the random chance element will have been factored into the card design, it’s something that people like more or less I suppose. I mean, if you’re playing Dominion in the first place you’ve bought in to the concept that there is significant luck involved, but I can see for some people that there comes a line where luck has the potential to overtake skill.
I’m not really sure that 15 unique cards were really needed with the Loot concept, seems to me that it would have been just as interesting with fewer (and then you might have printing room for more copies). I don’t play very often with more than 2P but if Prize Goat is your only trashing option then I could well believe a lot of 3P games end up with a huge imbalance.