The main benefit you get from being a consultant for a while is that you get to learn just how much BS lies at the heart of most "consulting", as well as the companies that like to hire (tons and tons of) consultants.

That is, mostly consultants are hired for (as other have said here) psychological / CYA reasons, rather than for the actual business value of the advice they provide (which is often mediocre). And of course when it comes to technology products, the actual (source code) contributions of consultants, dollar for dollar, is often especially low, indeed.

Another nifty thing you'll learn when doing consulting, which is hard to learn otherwise, is that the higher rate you charge, the more people value you and you work, for some reason. Which is a very useful thing to have a visceral, bone-marrow-level grasp for, indeed.