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

[Rydin]

That's not exactly true. What do you call roaming parties in XI? They move(d) A LOT, and have/had plenty of time to keep a party adequately healed. And they did it just fine w/o moving while casting.

There is a difference between moving *during* fights and moving *between* fights

As for the Behemeth running towards the city example, that's what bind/shadowbind/provoke is for; at least, what it "should/could" be for in the event that SE adds that sort of content. Bind the enemy, or get his attention by spamming hate moves, then he "runs toward the city" again once he resets hate (just an example).

That could still be fun...