In my experience, when a platform adds support for something like that, apps quickly start requiring that you have the feature on, even unrelated apps. For example, a ton of apps, especially sketchier ones or ones aimed at children, ask to see your location even though they have no legitimate use for it. If you don’t allow it, you can’t use the app. Obviously what they’re using it for is datamining, so I’m worse off than in the world where the app isn’t able to ask for location access.
Obviously it’s good that some apps do have access to location! I play Pokemon Go and use third party map apps! But I think the world would be better off if the requirements to be allowed to ask were more stringent.
For something like web bluetooth, while there are some rare use cases, I’m sure that pretty soon it’ll start being another tool for removing privacy and I’d rather err on the side of caution.
From an entirely separate side, I think that we’d all be better off if the entire web was much simpler to implement. We’re almost in a browser monoculture now and we wouldn’t be here if it weren’t so difficult to implement a browser that supports modern websites.