I guess artists are looking for their unique sound and just like to experiment with a multitude of thing rather than just sticking to an all-in one package. I'd personally go for a basic amp that had a good character but didn't have tonnes of processors and digital microchips in it, after all I can add all of that later through digital FX pedals. I think you might also find that professional quality racks that focus on a specialised range of effects sound better then digital all in one solutions however the new Line6 range is pretty damn good, you'd have to be quite picky to really care.