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

[Jinko]

Im all for movemenet interrupting spellcasting, that being said I agree with Jinrya-Geki and hope that PVP doesn't destroy this games PVE balance like it does in other games.

I'm not a fan of spell casting being interupted by monsters though, espeically if its going to be 100%.

PvP issues did not influence his decision on how solo and party playstyles will work.

Reading his post most of it is regarding PVP though, it definately comes across that the decision was made based mostly with that in mind if you ask me. (perhaps you interpreted it differently though)