I can appreciate the fact that they need every one that they got and they're rebuilding them and such, but that's a different argument from the "they're too dangerous" crappola that the government trots out.
Sorry, but my tax dollars paid for (or, rather, pay the interest on the national debt that pays for) those vehicles. I should be able to buy one, and either use it off-road, or retrofit whatever I need to meet applicable standards so that it can be driven on the road. There's a pretty big difference between "sorry, we just don't have any surplus to get rid of right now" and "even if we had one to sell, you couldn't buy it."
Sure, "off road only" is hard to enforce- but that's NOT uncle Sam's problem, just like it isn't John Deere's problem if you drive a Gator on the road, or Yamaha's problem if you take your Raptor out on the streets. As pointed out before, the only reason they're NOT street legal is because the design hasn't changed with the DOT requirements through the years of production, so even a 2008 HMMWV is, really, a 1985 model by design, with a few tweaks here and there.