I mean, it was already remade quite recently, and successfully; the only reason the BBC possibly thinks this is a good idea is that they don’t know about it. See, the people who remade it changed the title. To 28 Days Later.
28 Days Later is effectively Triffids with fast zombies instead of plants – from eye operation, to deserted London, right down to the villainous military guys. And because it’s really a very good movie, and since the 70s Triffids adaptation (minus good-enough-at-the-time plant SFX) is really very well done, why remake? Because of 28 Days nicking all the best imagery that hadn’t already been taken by the 70s adaptation, you’ll just be repeating the idea rather than providing anything new.
Still, I don’t know exactly what they’re thinking, so I hope that in the future this doubt will sound like someone complaining about the rumours about the new Doctor Who or Battlestar Galactica before we actually got to see them. That’s my hope, anyway.