It's a fair point lato but my issue is that, increasingly, sites are being tailored to perform on search engines. Not necessarily due to relevant content but due to hack, tricks and a knowledge of how
SE's work. To me, it would be a better benchmark of a site's worth if it was coded properly (it's not about aesthetic by the way - it's about adherence to standards) and therefore ranked higher on SERP's. Not that content wouldn't be important - but proper markup should certainly receive more weight than it currently does.
The fact that there are people out there making a living by optimising sites for
SE's - when listings are meant to be organic, unbiased and natural - is cause for concern. That's not to say there's anything wrong with
SEO as a profession but it does point to an inherent weakness in
SE algorithms.