> isn't it also illegal to buy unlicensed securities
There are "safe harbors" like Regulation D [1]. This is how private companies issue securities. There are still rules about to whom you can sell your securities and the minimum information you have to make available to them. Needless to say, I have not seen an ICO promoter make use of these safe harbours.
unaccredited investors, oh my! When you brush your teeth do you make sure you have government authorization to do so? Also, I hope the toothbrush and the toothpaste were OKed by a government bureaucrat, because thinking for yourself is hard!
They've been warned, but what does that even mean?
Unlicensed securities that are not exempt from the law are illegal to buy or sell.
The implications seem clear to me. Again, IANAL, but a lot of people seem to be commiting felonies, even if they don't know it yet. These ICOs can ruin the lives of more than just the owners.