Moving will be made to interrupt spellcasting at a point in time...

[Estellios]

The skill limits were for this class revamp and obviously won't be a factor for the entirety of the game, especially when the level cap gets raised and we learn more.

It's a large enough change that they want to implement it ASAP so people can get used to it but they won't if they can't get it to work well with the current system. It balances out mages in more than just PVP settings and believe it or not there is an audience for PVP and if implemented well enough it could draw in new players, and that's always an improvement.