Is the premise that modern sites do not take studies on aesthetics/usability/effectiveness into account even true? I've moved into web development over the past 8 months or so and I regularly search for topics such as "log in vs sign in," "ok cancel button placement" and "optimal web page navigation."
It seems to me that there is no shortage of studies, opinions and hard evidence on display regarding the (in)effectiveness of particular web design choices. Granted not every google hit is going to cite a formal study, but a surprising amount do. Googling the above over the past ten minutes or so has given me references to a study on optimal text layout, a study on label placement/alignment, why dropdown menus apparently suck, and how presenting users with too many choices is detrimental to user engagment (admittedly this one was generalized to the web after the fact).
Right, the whole point is that there's a lot of studies, and professional web designers don't seem to use them.
So I'm working for a friend's company at the moment (friend is a small business owner who designs websites and a bit of an entrepreneur) anyway, I've persuaded him that we should research the empirical literature on what makes websites effective (which we've done a lot of now) and to advertise ourselves as being special by reason of doing this (which we're only just starting to do).
One thing that I found absolutely remarkable is how unfilled this space tends to be. Like a lot of things in the broad area of empirical aesthetics it seems like there are a lot of potentially useful results (c.f.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3485842/ ), but they're simply not being applied- either as points of real practice or of marketing differentiation.
A fascinating gap.