If you are assigning the property then the end buyer should want to see the AB so they see all terms they are assuming with the assignment. I won't sign an assignment without seeing the AB. I tell my wholesalers they are welcome to redact their price, but we usually find out at closing anyway.
I agree that some buyers may complain about your fee, but if the numbers work for them then it shouldn't matter. But it is important to know all terms within the AB because the end buyer will be held liable for all of them. As the end buyer, it is also important to be able to verify that the contract is written for the correct property and with the correct seller to ensure I'm not being assigned something incorrectly or that I don't intend to buy.
The investor and wholesaler should act with good faith towards each other to build a solid, working relationship for repeat business. It's a business of who you know, so maintaining a good standing within your network is vital.