The tools might get
written. But they won't be
installed on those routers, remote servers you're not getting to install stuff on and all kinds of other places where people who work with networks frequently want to be able to talk protocols from.
It's largely irrelevant to me if there are tools out the wazoo to work with some binary protocol if I'm unable to run that tool everywhere.
And there's a huge range between advocating arbitrarily complex and flexible text protocols vs. binary protocols. You can "easily" do text protocols that are picky about field lengths and that use formats that can be parsed much faster than the more complex protocols.
If your protocol is using a small enough, regular enough grammar, it'd also be fairly trivial to allow a binary serialisation of requests or responses as an option without much extra overhead. E.g. start client connections with a word indicating it wants to "switch on" binary and length prefix any variable length fields instead of relying on an end of field marker, for example. (Or make human clients type out a word to switch to the text serialisation).
But very few protocols are so affected by latency in request/response exchanges that binary vs. text is a huge deal. For HTTP moving to a pure binary protocol might make sense because of how heavily we depend on it. But most protocols are not HTTP.