lens - Aside from sharpness & speed, what are the benefits to photo compositionoptical quality provided by premium lenses over their cheaper counterpart?

I have gone through quite a few lens reviews and questions on this site that recommend expensive lenses over their cheaper counterparts. From what I've seen in the reviews, there is a marked improvement in sharpness (esp. at 100%) for the premium lenses over their cheaper counterparts (E.g. Canon EF-S 17-55mm vs 18-55mm). Besides this, many of the premium lenses also have a wider max aperture which may be fixed throughout its focal range, and this is a tangible benefit to composition. Build quality is another benefit, but that doesn't impact image quality.

So, my question is what other benefit does a premium lens provide over the regular lenses? Do premium lenses have any impact on image composition & photographing technique (I'd suspect that the added bulk can be a hindrance at times)?

Note that I am not considering specialized lenses like 600mm and the likes which do not have any regular counterparts. Also, by counterparts, I mean lenses having similar focal length range and apertures.

Answer

For one, Canon's premium lenses ("L") will allow you (with a matching body) to shoot in environmental conditions that are considered harmful for the non-premium ones. In a way it will have an indirect effect on your composition.

Depending on the amount of post work you are (not) willing to do, the premium lens will get you better color rendering, glare control, etc.