If you do a quick calculation on seat pitches you can see that to increase pitch by a full ten inches would only put up the fare by about one-third on most airlines. In fact the premiums for more space are way disproportionate.
I am old enough to remember all the guff about the 747 bringing back the golden age of flying, proper beds, lounges and bars, and so on. Into service it went, with less comfort (at least in the middle) than on a 707.