The trend over the last few years in web design is to get rid anything with gloss, or shadows - so prevalent in the early web. However, just like with underlined links - there’s a functional aspect at risk when those things that visually say “click here” are removed and just replaced with color.
Another example is glossy PayPal buttons being replaced with flat, Amazon style CSS buttons. Are they really better? I haven’t done any serious AB testing between the two, but my hunch is the glossy buttons are stronger and have the advantage of familiarity. There are millions of websites which have/had the old PayPal buttons on them. People instantly recognize them and have probably clicked on them too, i.e., bought stuff. If their PayPal transactions went without a hitch, then they’ll most likely have a positive association to the buttons the next time they see them somewhere else, something the new CSS buttons lack.