@Gargron The issue isn't that anyone's being forced to use an app. Folks are worried that this might signal design changes to the rest of the software that would kill the one feature Mastodon has to offer communities (the local timeline).
And if it's literally named Mastodon and promoted as the official app, you can't ignore the knock-on effects of folks signing up to smaller instances like mine with it. The #1 question that I get from new users is "how do I find folks to follow?" and as a small special-interest server that already has a curated community, the answer is always going the be the local timeline, because that's where folks with the same interest show up.
I won't be able to give that answer any more and it will 100% hurt new user retention to tell them they have to uninstall the official app and use a different one.
I think it's an interesting gamble, and I more-or-less agree with your reasoning about the federated timeline (though I'm specifically thinking about its use for harassment), but local is great and you're not the only person affected by your decisions.
Plural Café is a community for plural systems and plural-friendly singlets alike, that hopes to foster a safe place for finding and interacting with other systems in the Mastodon fediverse.