WS-* is big because it solves many, many problems. It's also big in the chatty sense because it's XML-based.
That does not make it a mess.
WS-Trust, WS-Federation etc. have already solved problems that OAuth 2.0 attempts to solve, which doesn't make it bad, as Eran states. Bad is subjective.
Whether someone chooses to use it or not depends entirely on the requirement. Choice is good.
- Choice in plug type for electrical devices
- Choice in power adapter connection for cell phones
- Choice of driving on the left side or the right side of the road
- Choice of location for the brake pedal in your car.
Most anything that is used to interface two items, as is oAuth, is better with fewer choices. Choices increase complexity and cost for both sides of the connection and reduce the number of solutions that are compatible. However, for some reason this fact is often lost on technologists.
In short, it's collective name for many Web Services specifications that are still heavily in use in "enterprise" world. It's a mess.