I don't dispute they want the final product in the end. They agree with Oculus' vision so they back them up. But why are people feel upset?
Two reasons:
1. Some people feel they are entitled to share the acquisition because without their early support (via KS crowdfunding) Oculus may never get that $2B acquisition, or/and
2. They dislike the acquisition and they feel entitled to have a voice. Like public trading companies shared holders should have a say in the company's direction and the company is responsible to maximize shareholders' profit
Either one or combined.
If the deal is clear from day one, which is that you, the backer, will only receive the perk as promised, and any penny you give to the project will be used to keep the project growing. But you don't have any say in the project, because, they never said they will let you be a shareholder. They are not going to discuss acquisition with you, because, this is a private company. Fan support is essential to keep a project like this growing. But business is business. If you think you are better off with some extra $$ in your pocket and getting a powerful parent looking after your project at the same time, you probably should take the acquisition.