I don't really play SAM myself, but I've always felt that folks were salty over the removal of Kaiten because the animation is now gone. I feel like they need to find a way to add that animation back and folks would be happier.

That said, as someone who's played Warcraft for years, even long before the mass WoW Exodus, having an ability that you press before every big weaponskill to increase its damage (or potency, whatever) is bad game design in every sense of the phrase. I don't care how hard you try, you're not going to successfully argue this fact. It just is. Ultimately I don't play SAM enough to determine whether or not they increased potencies enough to offset Kaiten's removal, but I would wager that its removal is going to lead towards better game design in the future, regardless of what every other player personally believes.