I guess it depends on the state. I understand that in some states, as Julie mentions, it's a requirement, because otherwise you represent the seller.
In Illinois, we have buyer's agency, and the agent is presumed to be working with the person he/she is working with (in other words... if you're working with the buyer, you're a buyer's agent... with or without an exclusive buyer's agreement).
We get a lot of resistance to buyers signing "anything" let alone a document that basically spells out that if they buy a house, the agent gets paid, and if the listing doesn't "co-op" the buyer's agency fee, it makes our buyer client responsible for that payment.
While I agree, that the EBA offers a great opportunity to sit down with the client, and spell out exactly how things work and who's responsible for what... you don't actually NEED the EBA in order to sit down and have that conversation. I feel that if I explain things upfront, and if I treat my buyer clients well... they will stick with me, they will buy with me, and I will get paid. I don't feel comfortable having my client (whom I'm supposed to represent) sign a document that, for the most part, protects ME (not them), and binds them to me, and makes them responsible for my commission.
I feel if I do my job properly, we'll have no problems. If they end up buying from a FSBO, or new construction, without me, and I don't end up getting paid, then I've not educated them well enough to understand that they need to include me at the first showing... and shame on me, not on them.
I'm not going to enforce the EBA so that they now have to pay me out of their pocket.