So what could they do? Never update the justice/valor points items? If it was still only 346 blue items, you would have no choice but to do older raids in order to clear Dragon Soul.
That's all i can think that would give us a reason to continue doing older raids. But then, that would make the point system completely pointless after a few heroic runs, not to mention no one but new alts would run heroics anymore. It's either kill heroics or kill older raids. And since most WoW players would rather do short heroics than spend 3 hours into a raid, i guess that's what Blizzard prefer to do.
Although, with the LFR now, they could do something different with MoP where doing LFR raids replace heroics once you're geared enough, since they only take 1 hour to do each thanks to their low difficulty and being split into 2.
