As
@dmtaylor said, it is faster, which seems to have been a primary objective for the OP. Another reason is that some folks don't have the ability to achieve the typical low temperature for a traditional lager. Fermenting warmer also allows one to use less yeast. Pitch at ale rate vs. traditional lager rate.
There are lots of traditionalists that think this is all foolishness and that the "correct" flavor is sacrificed. Certainly many lager yeasts do not work well with this method and those that do are being used "off label". With some very clean flavored (no flavor) yeast there is likely little or not flavor difference. Others do produce a difference at warmer temperatures. Flavor, better or worse, is very subjective.
It would take a pretty complicated experiment to do a truly subjective comparison between the same beer fermented as a traditional lager and a warm fermented one. One would have to come up with a process that eliminated any other variables other than time and temperature. And that in itself is two variables.