I can’t tell you what the devs are thinking, but I would assume they tried to adopt the Console mana generation rules and are now regretting it. After all, the lack of surges on 4-matches always seemed like a bug. Here’s my mea culpa on this:
As to troops like YC, the team you provided actually feels somewhat safer to me having tried it in the beta, since when she does misfire, the opponent isn’t able to chain as wildly as before. This is one girl’s opinion, though. I don’t begrudge you your own.