In order to make ultra wide angle lenses, a retrofocal group is usually used. The retrofocal group is essentially a reversed telephoto at the back of the lens.

Now, to transition from the ultra wide angle region into wide and normal fields of view, we'd have to eliminate the retrofocal group from the optical path. That's not impossible, but it requires "switching out" the retrofocal group, similar to some lenses that have built-in teleconverters that can the switched on or off (such as the Canon EF 200-400mm f/4L IS USM Extender 1.4x, or Nikon's recently announced AF-S Nikkor 180-400mm f/4E TC1.4 FL ED VR).

In addition to removing the retrofocal group, the wide field-of-view collecting concave front elements (the fisheye elements) need to be removed or "switched out".

Conversely, to get into the superzoom range, you'd definitely need a telephoto group in front of the lens. But similar to the retrofocal group, you want the telephoto group to be removed from the optical path when you're working in the wide angle regime. Because of the need for a useful maximum aperture, the telephoto group has to be large, much larger than the retrofocal group. In rough terms, the glass has to be much bigger at the front of the lens than at the rear. So a switchable telephoto group needs a compartment to store the group in the lens, but out of the optical path. It would look like a goiter at the front of the lens.

When it comes to designing optical formulas, the components of a lens aren't designed in complete isolation of each other — decisions made in one group of optics impact decisions that need to be made in other groups of optics. So if you don't design the main group(s) and focus group(s) with the retrofcal group in mind, then the ultra wide angle performance will suffer. If you don't design the main and focus groups with telephoto performance in mind, then the telephoto performance will suffer. But by needing to make each of those groups removable or switchable, you're requiring mediocre performance at the very best, while also saddling the lens with huge size and weight penalties. And likely prohibitively expensive. And the lens would probably be outperformed by a small group of 2 or 3 kit lenses covering the same focal length range.