Why do you think a banks NFC payment app might not be secure? If ios is a platform then another NFC app could be as secure. Regardless, users should be given a choice. You can continue using Apple Wallet app, some other users might prefer other apps.
Choice isn't always good. Especially where consumers don't really understand all the implications. My mom doesn't benefit from choice here, she is actively harmed by it, she knows it, she uses Apple to avoid it.
Then nobody will use them if Apple allows them. If they do it like Google, by default users cannot sideload or install alternative app stores anyway. It's opt-in. Why do you want to prevent people who actively want to do these things with their phones from doing them?
If Apple's goal is to make things as "easy" for people as possible, then they should just not have any app store at all. And they shouldn't offer different configurations. They should just release an Apple iPhone that comes however it comes and nothing about it can be modified. That would be super convenient!
I don't want to. I want Apple to make the decision. I want Apple to make 1000s of decisions for me around my phone. They seem to be good at it, at least with respect to end users.
And, no, a non-app store phone wouldn't be convenient. Uber is very convenient. So is my banking app. There are dozens of very convenient apps on my phone.