Pricing in the exchanges is predicated on the assumption that healthy people are going to enroll along with the sick. If healthy people can keep a lower-cost plan, they will. The population in the guaranteed issued ACA compliant plans will have an even higher average claims level than originally projected.
Yes, it's for a limited period of time. But it's going to do major damage until things stabilize...and it's like hitting a bell every time you change the basic rules. It takes a long time before the vibrations die out.