For me legroom is one issue but a bigger one is width. I am wider than a standard domestic coach seat such that if fly in one I'm competing for armrests or I'm hanging out into the aisle or I'm sitting in an uncomfortable position of squeezing my arms in. It's incredibly unpleasant.
The biggest problem for most airlines (from my perspective) is that coach continues to shrink and the jump to business can be massive like from $300 to $2000. That's where Premium Economy and things like JetBlue's Even More Legroom are good.
But I will optimize to have a longer trip with a layover than fly direct to avoid this problem. For example, I'll fly on American's older 737s and 767s in "First" transcon via DFW or ORD for ~$1000 return rather than $500 in coach direct or $2000+ in business direct (both of the last two on the newer A321Ts).
Premium Economy is a mixed bag though. Cathay Pacific's is quite good (with some caveats). British Airways I hear is PE in name only (well, name and cost for some reason).
Still, lie flat business class, particularly on international long haul is hard to beat.