This thread is such a goldmine. It's already been explained multiple times here: a second charge would mathematically change very little in the grand balancing scheme, since a second charge effectively means one more use over the course of an encounter. It would make its use as a healing ability more valuable, make its use as a damage spell more flexible than just blowing it on cooldown, etc.

And you'd think the Sylphie brigade would be keen on that, but ohhhhhhh no. STOP OPTIMIZING! SKILL IS BAD! EW GROSS ASSIZE SHOULDN'T BE IMPROVED AT ALL SINCE IT'S A YUCKY DAMAGE SPELL!

There's a population of players who hates the idea of anyone else enjoying the role, and it ain't veterans.