As Metamask is able to let users freely customize their RPC/node endpoint, I wonder if some users choose to change their default RPC other than Infura, does there will be some downsides from the users' side? Technically, no matter what node the user pick, it shouldn't affect anything at all about how the way users interact with the blockchain right?
Metamask is just an "interface" to the ETH blockchain. That means people can simply change the RPC URL to their liking if they find an specific node to censor transactions. The project is open source too, so if there are risks of "centralization", anyone can just copy the code and launch a fork that's decentralized. Metamask developers are not stupid enough to make their project centralized, because that will make them lose many users. We should "keep our eyes open" just in case, in order to help preserve crypto/Blockchain tech's decentralization.
Unfortunately, that is something people haven't realized for a while now. If you really want to make sure that you are not getting any breaks or troubles for a company, just take over and use it yourself, it is your chain and your address and they are simply just an interface. In any case, I feel like this was something we shouldn't really focused on too much anyway, not a really big deal.
Metamask is a great product, but it is an interface software and nothing more, there is no need to make a big deal out of them because they are not as big as we think. They are used a lot, but also could be replaced in a single second and that leaves them powerless and caution.