I think you're absolutely right, Vnuk. Though there are may be other considerations for mass producing these things which other people mentioned in other answers, there's really no good reason why you can't easily (or at all) find that type of screen. I suppose they are on sale in China / Japan, possibly also South Korea, though. I am guessing, but I'm nearly sure at least one of those lands offers a good version of what you are looking for.
The demand really ought to be seen to be there in some identifiable, significant amount. Sitting back at my laptop typing, I realise there is little difference at all between the physical dimensions involved, my body set back, my hands out front on the keyboard and my eyes going to the screen. It's all more or less the same dimensions as when I use the big desktop when I'm at my parents. Except, as usual, I am looking down substantially at my laptop screen, even at a table, the one disadvantage to the greatly versatile and portable machine. Just now, since you've mentioned it, I'd rather the flat screen be flat on the wall, and very slightly above my eye line.
I have come across 15 to 17 inch digital photo frames which are also digital (H.D.) video film players and have U.S.B. and memory card inputs, made for hanging on a wall. Here is hoping, for one solution other than the most obvious solution to the problem (and not giving up on that - let's have the small monitors, please), that these might develop some kind of H.D. computer monitor input ability not too long from now. Perhaps it has happened already. It takes a lot of searching through The Web network sometimes to keep up to date.
(There were a number of Full H.D. 1080p versions of the digital photo frames, I remember, and some were 720p. But I've never seen a 1200p video and photo frame at 17 inches. It's a good idea to remember that such definition, 1200p, for that small size in inches is pretty phenomenal in terms of what we're used to. It must be amazing for photos. Does your monitor upscale or fill-out films?)