As mentioned before on this thread, I think by definition a flat response implies that the speaker faithfully reproduces the signal as fed to it. I don't see why that can be a bad thing, although I can see that certain colorations imparted to the sound may actually sound very good. Personally, I would rather my speaker did not impart colorations. This is why I would really like to hear
these and these and
these. This was the design philosophy of Dunlavy speakers, (which were never in my price range

). However this
discussion may be relevant (see especially, page 2). Another relevant factor is how much flatness digital correction (MCACC, YPAO, Audessey) can achieve, and whether such programs have become sophisticated enough to make corrections without introducing audible artefacts, as discussed
here.