Senna at Williams

I'm pretty sure that once both of the 1994 Williams cars had been properly stabilized after the FIA outlawed Williams unique active suspension, Senna would have won that years world championship albeit by a few points after a troubled start. But would they (Williams) have retained Senna. My reason asking is that it seems in their history to dispense of any drivers that win the driver championship crown. Look at their unwillingness to keep ace drivers like Nigel Mansell after winning for them in 1992. Prost won in 1993 and he specifically mentioned he would not be in any team where he had Senna as a team mate. So they signed Senna to get shot of Prost. Damon Hill won in 1996 and Jacques Villeneuve 1997 both for Williams, and they to were shown the door. I don't know if Frank Williams just doesn't like any drivers to become too complacent in his team. Anyone know or speculate why Williams just seem to leave drivers of this caliber high and dry once they have achieved the world championship.