Secondly, you can "side load" iOS apps as well. You just have to go through a process of jailbreaking your iPhone which is not illegal but it may void the warranty.
When you buy the iPhone you are also buying into the platform. If having multiple options for app stores is a necessity for you then an iPhone is the wrong device to purchase. Buy something else. There is nothing wrong with voting with your wallet as there are other phones on the market for people to buy.