It's not intended to be that way. And contrary to what Parallo said, the devs have not decided on character skill in the eternal fight between player skill vs character skill, and if they really wanted hit&run duels to vanish, there would be a really simple solution to achieve that goal. The current situation, as some have already mentioned, is a side effect, that was not planned, and it will be fixed some time soon(tm)
There will be other solutions on how to even out a fight between a warrior and a mage, but I'd rather think it will happen by more powerful spells. The base is already there (many attack spells, regeneration spell, shield spell, absorption spell, etc), all it needs is a bit of balancing, which will be done in the future. And yup, casting a spell while running should be possible, as it would only be fair.