Technically, the actors could pack it up and go into improv. Heck, back in the REALLY old days, theater (or some of it, at least) was totally improved. I recall hearing about that when I took drama. Everyone kind of knew what they needed to lead into (such as, if the troop had a juggler, somehow a situation needed to be arrived at that allowed him to juggle) but there was no actual script.
I find it ironic that all of this is a side-shoot of someone claiming JMS had no respect for actors. A charge which seems unsubstantiated from everything I've ever heard, and those who have really followed his career and public appearances quite closely. Besides, how can JMS be blamed if an actress decides to walk away from the job? It wasn't his choice.
I always got the impression that the actors loved to work for him, and especially loved his scripts and character development. Even Claudia did not leave over an argument with JMS; she left for career reasons (no matter whose version of events you consider, that much seems to be consistent). If the actors had no complaints, how can we?
As far as which is "more important", it's a useless argument. In a collaberative effort, the project is the result of everyone doing their thing. Change one element, and that "thing" changes, either slightly or drastically. You might as well debate which season is more important. It isn't really a valid question, since everything on this planet evolved according to the conditions that our four shifting seasons gave us.
And that's my very long-winded two cents in the whole matter.