There's a reason for it - tutorial purposes. New players, and i mean actual new players who have no idea how MMOs work, struggle to remember to press a second or third button so they need a long time to ease themselves into it. It makes sense and i agree with it.
It's fine though - if you're so skilled i'm sure you can easily level up super fast and get those extra skill. I'd say having fewer skills actually makes the low levels more strategic where you optimise GCDs so you can pull more enemies faster.