The 70's for me is divided right down the middle, literally. First, '70-'75, and then '76-'80. The first half of the decade being the best with the last half of the '60's, was the best 10 year period of music IMO. The last of half of '70's decade, well, wasn't a time period when rock music didn't really "progress" and it can be argued that some of the sub-genres from this period were less creative and artistic. With that being said, certain forms of rock music {is disco a sub-genre of rock(?)} from '76-'80 didn't appeal to me but did and still do in some degree, helped developed rock music moving forward, even if I consider it not to be of a high musical merit or an actual dislike of it's structure and form.
The early '70's were more or less a continuation from the late '60's as rock experimented and fused together different elements of other genres of music, for example; jazz, blues, country, classical, amongst others. At this time period different sub-genres took hold and were defined like progressive rock, jazz rock, hard rock, heavy metal, etc. Artists that led the way were Led Zeppelin, Black Sabbath, Yes, Pink Floyd, King Crimson that were a huge influence of others to follow.
Just like in any era or a certain time period there is forms of rock music that can be said, again, one's point of view that was, well, not very good. The early '70's did have some music as I see as not being very appealling to me, like some power pop artists, sunshine pop and "bubblegum" groups such as The Archies and Ohio Express, and of course the Bay City Rollers.
The last half of decade for me, in the most part was disappointing. Most of the "giants" had already been at thier peak and were declining, prog became stagnet and turned in the direction of incorporating a pop/rock element, disco was so pompous and simple, no artistic merit and was more about the production than talent.
Not being a big fan of punk, though I am fan, captured the anger and energy that came with social unrest and the anti-establishment sentiment and to a degree the "mainstream" or pop music of that time. For me, hearing that rebellion, lawlessness, and disrespect for authourity does in some ways pertain to my disposition and my past. Some say punk was a step backwards and even injurious to rock music. I don't see it that way as punk did and does have much more influences on rock music than did disco.
I think for me, the '70's are my mosted listened to decade. To say music from any decade or era is bad, awful, terrible, or any such negative statement IMO is ludicrous. That is such a general statement, and in my conclusion is being close minded, ignorant and arrogant. I better be careful in what I say because I've been guilty of this also.