From one of the comments at Coindesk (pliv84) :
The big value, in my mind, is that it functions just as any other ETF, meaning you can buy it like a stock. Sure, there is one other BTC exchange that does this, but it is very thinly traded.
For the masses, who don't understand where/how to buy BTC, this makes it a lot easier for them to add it to their portfolios.
The corollary here is the gold ETFs. In the years after they launched, gold price skyrocketed. It makes sense - make the security easy to buy, and more people will feel comfortable buying it.
(I'm using that quote to clarify why the ETF part is so important, plus the fact they can also handle big institutions that are excluded from the New York BitLicense)