The obvious question is whether that actually matters all that much for securities, since the broker/exchange adds negligible risk and overhead for the buyer relative to the trust in the public company needed to buy a stake in it and the costs of meeting regulatory requirements for public companies.

Anybody who's more worried by the potential complications of T+2 settlement when purchasing blue chip stocks than the Wild West world of ICOs shouldn't be investing.

That is indeed the right question to ask.

Maybe it's less about trust and more about permission. With token based securities I could trade with whomever I choose whenever I want.

Interesting to see how it turns out in the end.

What happens if a trade that is illegal under the law of the country of the seller/buyer/exchange? The courts would be completely powerless to undo the transaction. Again it seems to me the main and only attraction is evading regulation.

And you can maintain custody, so somebody isn't loaning out your shares.

There's a 95% accurate O(1) solution to determine if an ICO transaction has integrity.