this sense of bloated pretense gave free reign to other rock acts to do the same, & tah-dah, out birthed (or at least inspired) progressive rock - the most overblown genre of music to ever have been created.
Oh, and I'll point out that, yeah, most prog-rock is pretty ridiculous. But I think certain bands, the Floyd in particular, manage to surpass a hefty load of the ridiculousness by being originals, making a sound unlike anything else, feeling free to experiment with some really bizarre sounds and techniques, and trying to disconnect themselves from the notion of the band consisting of a mash-up of individual personalities, and instead presenting a whole being to the audience. In fact, when Floyd was touring the Wall in the early 80s, the first number, "In the Flesh?" would be performed by the band from offstage, while a seperate group of men dressed like the members of the band would stand on stage and mime along as if it were them playing the song. This was to play off of the fact that, despite Floyd being continually successful, they were technically a one-hit wonder, having only reached constant radio-play with "Money", and few people were able to name the members of the band or recognize them based on physical appearance. Mind you Floyd was an underground act until 1973, when Dark Side of the Moon blew up. I just think that is ingenious.
But, I am a huge fan of experiential music, and I don't think other prog-rock bands really met the level of experimentation as Floyd... They couldn't, really, Floyd pretty much set the standards for the genre from 1969-1972 by producing 20 minute songs, rewiring wah pedals, sampling sound effects, and releasing lengthy, ambient, noise-jams, lacking traditional structure or melody. These are mainly the reasons that I still enjoy albums like "Atom Heart Mother" and "Meddle" over "Dark Side of the Moon" or "Wish You Were Here".
And beyond that, prog-rock, in a way, lead to one of my favorite, if not my favorite, classifications of music; post-rock, a genre that seems to be at its underground height right now with unconventional song structures but the exact opposite personality and mentality of prog-rock.