The advent of blue LEDs, a few years ago, seems to have become a cutting-edge fad with some equipment manufacturers. Sporting blue LEDs may indicate technical savvy to some buyers and, when new, blue was better.
The more recent use of blue LEDs to light up vacuum tubes, while cute, seems like a waste of money which could be better spent elsewhere in the product. Of course, when some of these amps cost thousands, I suppose artificially lighted blue tubes are but a tiny fraction of the cost. Still, this practice of azure highlighting of tubes has me singing the blues.
One of my, still favorite sights, is watching a power tube's internal, blue gas, dancing to the music it's amplifying. Now THAT's the real, blue, deal.