It's often hard to make api design decisions because people will always find something that doesn't fit well for their purposes.

Here, your change is limiting in case we want to only fetch dialogs that are not pinned. The raw API actually provides two distinct methods, messages.GetPinnedDialogs and messages.GetDialogs. For convenience, pyrogram merged both methods into one. Maybe we should keep two separate convenience method too: get_pinned_dialogs, which would return a list of pinned dialogs only and get_dialogs (which should be turned into a generator and have iter_dialogs deprecated) with an optional parameter exclude_pinned. What do you think?

I like the exclude_* approach.