I think you ask an interesting question because I have researched Service Broker as an applicable solution to issues I've faced on the job.

Why haven't we chosen it and looked at exploring other options?

Service Broker most certainly stands on top of solid core technology, is robust and transactional, and can handle our load - and we need the reliability, etc. but -

1. The configuration one needs to go through to even get it going - permissions, message contracts, queues, schema, etc. are too complicated (too many/too heavyweight).

2. There is no MSMQ "dump" to easily pass messages to other tiers - at least not natively and easily.

Our primary need has been to emit "events" from SQL related operations that could essentially be broadcast to other tiers/applications/components that are not SQL, and everything we end up working through goes back to polling the server.