Agreed with the above. But economy is all about economy. Cheap is more important than comfortable. Customers that won’t pay a £500 premium for a flat bed often won’t pay a £20 premium to have 34 inches rather than 32. Commercially, airlines have to make economy cheaper rather than better.
Premium classes have to be made better rather than cheaper (flat beds etc.). This creates a bigger and bigger gap between the two both in terms of price and comfort – hence the filling of the gap by new products such as premium economy, extra legroom seats and, now, impromptu sofas.
Airlines won’t like issuing ’empty seat tickets’.But it would be the simplest thing in the world (and therefore inordinately difficult) to enable a passenger to ‘block’ a seat at booking or OLCI, for a fee of course.