For me lack of backwards compatibility and lack of ports to PC or other digital distribution platforms translate into a lack of shelf space. Lets think about this for a minute, Im one of those gamers in their early 30s and Im a little late to the life train just having gotten engaged, no kids (that I know of), and a steady career. Since Ive been gaming there has been the NES, SNES, Sega, Sega Genesis, Playstation, Nintendo 64, Dreamcast, Gamecube, Playstation 2, Xbox 360, Playstation 3 for consoles. This is not including the mobile market that consists of a wide variety of handheld gaming devices, tablets, and various phones. That said, I dont have room in my house for 11 different consoles let alone all the physical copies I have.
Backwards compatibility removes the need to keep old systems which also frees up space in your home. This is also one of the few reasons I like digital distribution platforms for PC and PS Vita. I dont have to have a closet full of consoles disks, cases, cartridges and more just to play older games I love (at the same time I dislike digital distribution because I cant control what happens with a companies servers while I can control what happens to my physical copies).
Things get more complex when we talk about exclusives. You cant transfer a copy of Fallout brotherhood of steel (Im pretty sure that was an xbox exclusive) to Xbox 360 (I know cause I tried to) because its backwards compatibility was crap. Presumably I still wont be able to do it with the Xbox One. So I either have to keep my old xbox or rip the files from my physical copy and put it on my PC to emulate it. How many people have the technical know how, let alone the equipment to take files from physical copies and put them on something else? Not many I would guess.
When I was much younger and it was just the NES and SNES I had a similar attitude. "Its no big deal, we have 2 consoles instead of 1" I would have said but by the time I had my NES, SNES, and playstation I started realizing that it was kind of a pain in the butt to find all the parts to one console if I wanted to play a certain game. Plus lets be very clear, can you even hook up an old NES to the new smart TVs without adapters? I dont think you can. Today Ive got my own place, my fiance has moved in, and in the next year or two Im going to be married and might have a kid as well. Room in our house is finite and backwards compatibility would do a lot to clean up some of that.
Not adding in backwards compatibility at this point just seems short sighted and inconvienant to the consumer.