Onya, mcgrath.
Except ... in my case at least, now that I've retired, I can no longer pressure the bean-counter into Business Class tickets on the company account.
So, if I need to go somewhere at short notice, cattle-class it is.
The real point about seat-width is that, while you yourself might be of relatively slim build, the persons either side of you may not be.
Because of this, you'll find that your corpulent fellow travellers invariably spill over into your allocated seating space.
It can thus be quite unpleasant - particularly when many overweight people can also tend to be malodourous.
The sympathetic looks on the faces of the cabin crew don't really help much.