When I first started Horizons, I'd played every other MMO on the market, and I've also played some new ones. All their controls seem to be the same for the most part.
My suggestion is to implement the mouse buttons to function differently. As an option, you can set left-click+hold to move the camera around the character with clicking on empty space and holding it down. This would make things easier than using the number pad for camera angles.
The second would be to hold down right-click and hold it for turning your character. I know middle mouse wheel can do this, but I'd like an option to set it to right-click+hold.
And last, holding down both, moves the character forward and turns the character at the same time.
Also, defaulting to W S D A for movement keys (rather than strafing) and SPACEBAR for jumping so people that play other games can jump in and use this. It's sort of a standard in most FPS/MMO games, but I know the way things are have been the standard for horizons.
Everybody I've talked to has remapped all their buttons to this, and this is only a suggestion, really.
I know these changes can be made player to player in settings (except the mouse options), but it's easier from a gamer's point of view to just jump into a new game and already feel familiarized to the controls. They have enough to familiarize themselves with anyway! Those that don't play games often or have never played this game before, will have to learn the standard Horizons controls anyway, I don't really think it's a bad idea.
The only drawback are those that have used the same controls unchanged since they installed the game.
Really, a fix would be having the download of the client have these familiarized controls already implemented, rather than getting into the game and spending time to change everything. And if you're new to the game, you'd have to learn the controls anyway.