I'm another one who agrees with JimBob.

I got excited about external activiation but this is service broker talking to an external app, not an external app talking to service broker.

There is already considerable antipathy towards databases in the developer community. The answers in the application layer now what's the question?!??!?

By the time you've set up service broker and got it running they've deployed their RabbitMQ solution and it works.

Factor in a number of 3rd party platforms containing their own ORM and even the idea of calling a stored proc is anathema to the dev teams.