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

[Agoven]

Casting requires concentration...and if you move you interrupt your own spell. If they do this they need to establish visible spell range zone and also spells need to be powerful since they'll be hard to cast.

[Neptune]

Casting requires concentration...and if you move you interrupt your own spell. If they do this they need to establish visible spell range zone and also spells need to be powerful since they'll be hard to cast.

I doubt they'll do that, but I like your suggestion. There should be a bonus to spell damage if you stand still, simple as that. On the other hand, doesn't it require greater concentration to cast while moving? If you have high enough intelligence you should be able to use it to cast while moving.