I think having a variety of quality manufacturers represented in the same lens mount is a tremendous advantage, and one that many people do not understand or appreciate.
Some people enjoy using black and white, some color, and then of course there's the millions of possible permutations of exposure, film and developing that allows people to be truly creative...sometimes a painter will use red, sometimes blue, but only a fool would argue that one color is better than the other.
In almost any other camera system, with the generous exception of large format, photographers are hobbled in the choices they can make by lenses dedicated to a particular camera..if they want a different look, then they have to buy an entirely new system.
I would love it if all the manufacturers of SLR cameras would standardize their lens mounts to allow easy interchange of all the different lenses...It will never happen, but it'd be lovely.
Imagine being able to use your favorite body with your favorite lenses for a particular task....a canon Eos 1V with a Nikkor Wide...or an F5 with Olympus lenses....lovely.
Sharpness is greatly overrated in lens design, many of the most widely acclaimed lenses in the world are not the sharpest, but they perform admirably in out of focus rendition, color cast, contrast, etc.
Some people also make arguments that a particular (often Leica) lens is "the sharpest lens ever...)
This is not only a silly argument to make, but also factually wrong....according to many tests, Canon has had several of the sharpest lenses in the 35 mm world for many years now....unless things have changed, their 200 mm f1.8 was recently proven to be the sharpest 35 mm lens ever.
And don't forget that the sharpest lenses in the world have nothing to do with 35 mm photography....
