Dear Steve,
Eh?
Surely a more meaninful question would be, "Would it really kill matte manufacturers to make mattes 1/4 inch smaller than nominal' or even 'Would it really kill Steve to cut his own mattes?"
Also, what's wrong with 11x14 inch on 12x16 inch/30x40cm instead of 16x20 inch/40x50cm?
For that matter, why do you want to print 11x14? It doesn't match many actual film sizes. You seem to be falling into the trap of 'that's what's available in cheap pre-cut masks, so that's what I'll print', then setting the trap of 'I want to print this size so everyone else should have to as well'.
Certes, I'd be irritated as hell by a whole new series of paper sizes, all 1/4 inch too big.
Cheers,
Roger