Well, that's half of the downside presented, the other half is that it's split be server/client connections. I assume this was done because it simplifies the tracking of the next stream identifier, because you can just keep a counter and increment, rather than a table of used streams to check a new random identifier against?

BTW, recent data shows that Firefox does (on median) about 8 requests per HTTP/2 connection, up from slightly more than 1 on HTTP/1.1

So, if we ever close a connection from having reached a billion streams we are in a very very good position.

Doubling the number of them doesn't make it more right.

Are you talking about Java?