I think it is a big deal (assuming we ever see a PS4 - good point LE) because I don't want to be spending $60+ a game and know in the back of my mind that it's won't even be compatible come the next generation.
Sony's commitment to backwards compatiblity was one of the biggest selling points to me, as I didn't feel too bad spending $30-$50 on a PS2 game because if it ends up being a classic, I know I can still play it on the next generation.
Even in 10 years time, there's just no way games can be 100% digital distribution. That'd put places like gamestop out of business (we woudn't want that..

) not to mention it'd mean even super giants like best buy would be slowly heading to their demise, because a good chunk of their sales come from video games and movie sales.
Plus, if you consider so many people (especially in Europe) dont even have internet, or live out in the country and only have dialup.. yeah, 10 years from now who knows for sure.. but the way things are going now, in my eyes, I just dont see digitial distribution becoming the complete new standard. (Though I'm sure it'll be an option.)
And the reason we're talking about the PS4? Because Sony's Phil Harrision is!