People have spoken with their wallets. The legacy carriers that traditionally had larger seats and more varied classes of service were eaten alive by budget carriers on Price.
I still can't believe we don't have a "get your own armrest class" option with minimal additional legroom for (say) 50-75% extra cost.
Orders of magnitude increases in cost will never be acceptable to the average person, or even the spending-their-own-money 5%.
I travel for a profitable business, and there's no way in hell they're paying 5x extra for us plebes to have a little extra comfort. I imagine only executives and the consultant class get away with it.
Comfort+ seems to be $99/way on trans-Atlantic and JetBlue's are $30-60 per leg on most flights.
I'm a (low) executive who probably could fly business class more (in the sense that our travel policy doesn't prevent it), but I choose not to as it's not a good use of shareholder funds. I only do it if it's <~$200 more or if I'm flying and going directly from the airport into a critical meeting. Routine travel and I'm fine in coach.
Source: 6'3" @ 230lbs. and I fly every week
"get your own armrest with minimal additional legroom" does exist, on many carriers. It's called Premium Economy.