Whether this is your right and privilege is determined by laws and regulations. At the moment, it is. At the same time, there are clearly different opinions as demonstrated by this thread, and your 100% agreement may or may not reflect how society overall feels about this issue or whether it's a good idea.
Neither does my opinion, of course. And either way, the fact that people like the Apple user experience doesn't mean they like or are even informed about the benefits and drawbacks of the iOS App Store model. They may have spoken for that model, or they may hate that model but still buy iPhones because they communicate with the rest of their Apple devices, or because the hardware is innovative and superior, or because they don't want to be tracked by a much scarier surveillance machinery. Without separating the parts and letting each compete on its own, we'll never know what about it is something consumers want and what about it they'd rather pass on.
I'm not calling for an end to products like Apple's. I think it's great that people have access to devices that follow clear policies and security practices which are guaranteed by a trustworthy party.
I do think, though, that this decision should be made by the user in the end. The opportunity to set defaults is already an extremely strong lever for the first-party vendor, and people such as yourself who like it as is have no reason to change anything about it.
I also think that competition can and should happen on different levels, and that control of e.g. hardware or system APIs should not automatically translate to exclusive control over the third-party ecosystem, unless the user explicitly wants this. One possible approach to regulating this, without preventing actual highly integrated products, could be to require the vendor to allow third-party app stores if the product ships with an app store itself. If the iOS experience is actually better with iOS App Store compared to a third-party app store with e.g. lower fees, better search and less stringent controls, why not let them battle it out and let the consumer decide?
It's important to recognize that Apple has created world-class products. It's also important to recognize that the existing duopoly is an extremely strong detractor against competition. It's like the government inviting bids for a giant construction project - if they require the bidders to do everything and the kitchen sink, then only the largest consortiums will be able to apply, whereas if the project is split into several reasonably-sized parts then smaller companies can compete as well and the end result will be cheaper, better executed and more accountable. I think we all agree that competition is a good thing, the question is how large to draw the boundary of what constitutes an integrated product and what should be considered out of scope, to compete in a different market. I think we owe it to society and to future businesses to ensure that a superior product still has a chance of succeeding in the marketplace.