Such "rubber" zoom lenses never come w/o strong distortion, either on short or long focal lengths (most probably at the wide angle end). I think all manufacturers of such extreme wide angle to tele zooms rely on a heavy-sided in-camera correction of all sorts of distortion, vignetting, and aberrations to keep weight, size, and price within tolerable limits. Personally, I therefore prefer dedicated tele or wide angle zooms (if not primes anyway) with much more properly designed optics.
I keep asking people to show me an example of how in-camera correction of distortion hurts a photo or is even detectable. No-one EVER supplies an example. If you have an example I'd be very thankful.
"Properly designed optics" are ones that make enough customers happy that the firm benefits. My 16/2.8 and 14-35/4 both have, I'm told a lot of distortion correction but I have never seen anything specific that is a problem.
Basically, optics design is a N-way tradeoff between size, weight, price, reliability, focus speed, center sharpness, corner sharpness, contrast, distortion, vignetting, bokeh quality, and aberrations that cannot be corrected in software. A traditional lens design that tries to improve distortion, will have to get worse on at least one or two of the other factors. But if we let the software fix what the software can fix--distortion and in most cases vignetting--then we can actually improve EVERYTHING else: make it a bit smaller and let distortion suffer. Improve sharpness and let distortion suffer more. Improve contrast and let vignetting increase. We can make ALL other factors better, and just let these two go to he11. Then... we can fix those two in software so well that... I think, though I'm happy to find out otherwise... the fix is literally invisible and undetectable. And yet you're saying such an optic would be improperly designed??
Note that for some astrophotography, I HAVE seen some cases where vignetting slightly hurts image quality. Since the corners are darker, they need a bit more boost in brightness... and since the sky's supposed to be near black, most of the signal there is noise... so it ends up being noise that's boosted. And yet even then, it's not complicated to minimize, and I haven't seen any other subject matter where it's detectable.
So, thanks to some members of this forum, I learned that in some very special cases, software correction of vignetting can be detected. But I still haven't seen evidence of detectable issues with distortion correction. Again, I would love to find out I'm wrong. Please share any relevant images you have and I'm actually quite ready to admit I'm wrong and you're right. But please share the images. (And if you don't have such images, maybe you might want to rethink your basic assumption here.)