You forgot the part where before, each time you accessed your inventory, they magically replenished during battle - which was the real problem, because that made them (infinitely) spammable. Fixing that might've been enough, but then, they'd have been horribly overpriced for the new economy.
I view grenades as gimmicks that are occasionally useful in sieges and village clearing, and the current low cost/larger amount carried/no replenishment works better with the changed economy than the old small amount/very high cost/replenishes model would have - if you want them to go back to replenishing between battles, that's an easy change to make, though.