...What?
Look, here's how it is. There's three big reasons why Microsoft and Sony don't want to add in mod-downloading for the consoles:
(1) They want a piece of the action, see? This might sound shady or greedy, but it isn't. Microsoft and Sony don't make a lot of money on the consoles the way HP or Toshiba does on a laptop. Microsoft and Sony make their money off software developers paying them a percentage in order to be able to make games for these consoles. You get it? Microsoft and Sony make their money off people providing content for the machines - games, in other words. If they make it so that people can provide added content for free, they've stupidly undercut the very basis of their revenue model. Because their money comes from licensing content, they obviously want it so that all (or at least almost all) content makes them money, and people providing mods for free makes them no money.
(2) User-generated content always has the potential problems of inappropriate content. Ever played Spore? That game is
all about user-generated content, and so they bend over backward to avoid people putting "Sporm" or inappropriate creations out there to be downloaded, because it's a game meant for all ages. Skyrim isn't meant for the little kiddies, but neither is it a Rated-M game meant only for advlts. M&S don't want some twelve-year-old kid's mom to come into the living room, only to find that their kid has downloaded a mod that turns all the women into strippers with gigantic boobs and no clothes, because then they're gonna be like "Obviously I can't let my kids play this thing. Maybe I should get them a Wii instead".
(3) User-generated content also will always have the potential for bugs. How many mods are there that have a bazillion glitches until the players beta-test it and then by version 5.3 the mod is relatively stable? Apparently M&S don't wanna deal with that, because console players expect their games to work consistently. Yes, I know that some people have bug problems with Skyrim anyway. Most don't, though, and with a user-generated mod, you know that a far greater percentage of people will have bug problems with at least the early versions of every mod. And even once the mod is relatively bug-free, there's still the incompatibilities to deal with; even two perfectly bug-free, play-tested mods can conflict, and M&S are trying to protect their users from that difficult user-experience.
That explain it well enough?