The reason there are multiple interpretations of the double slit experiment is because there are pros and cons in all of them. You seem to be describing a version of the Many Worlds Interpretation similar to the arguments of Sean Carroll.
The idea that the state of awareness of the observer collapses, but not the waveform, fails because the which-path information can be recorded but not yet observed by anyone. In this case nobody's state of awareness has changed in the least, yet the wave has collapsed or appears to have collapsed.
If the waveform is really multiple full universes, that raises more questions than it answers. What creates universes? Why don't these other full universes impact us in any way as they affect unobserved particles? Just how many of these alleged universes are there?
So, at a theme park there are 15 lasers each running through a diffraction grating, displaying a clear interference pattern for the entertainment of the audience. Are you claiming that each photon within one laser beam is in the same universe (not ours?) as one photon on another and so forth?
All MWI versions fail to explain how mere information existing can lock us in to one of those alleged universes. To be fair, though, all explanations are counterintuitive or seemingly impossible.