Even guards get tougher socially later on.  Social encounters scale with gameplay too.  In the beginning you're wooing the dumb guards so you can steal a horse, in the end you're wooing the king/queen to steal the crown jewels.  The King is not going to be susceptible to a DC 14 charm (unless you've got one heck of a dumb/lonely king). 
EDIT: I see you changed it.
That aside, I think the race needs a little variety.  Perhaps make the +1 score based on some simple tree varieties.  I'd counterbalance a good bonus to a mental score with a good bonus to a physical score.  Perhaps there are oak dryads who give a +1 to con, aspen dryads who get a +1 to dex and such.  Each could have lightly different physical appearances as well, I think it would add some creative diversity to a race that is essentially an elf succubus.