Because they are the natural state of things, normal dreams will always be not only possible, but almost always unavoidable.

I've been at this for a very long time, and I've found that the only real side-effect of it all is that there is a little extra awareness in my normal dreams. I almost always have a small sense that "this is a dream," even when my true waking awareness is absent. This has little effect on the dreams themselves (aside from things like making nightmares easily avoidable), so my normal dreams can be just as normal as they should be.

In other words, don't worry about it.