I like this wrapper for attributes, as it gives you more flexibility working with attributes and handles a few edge cases (which can possibly break code if you rely on some behavior from attributes) as well as providing more useful functionality (the support for other data types that attributes don’t yet support), and the first and last points you gripe about that this wrapper fixes, which I found useful.
That being said, the only gripe I have is that there is no support for Deferred events (as you use bindable events) which are currently in beta, but will soon become the default signal behavior. Other developers would find it a lot more useful if it handled some edge cases of that signal behavior implicitly, rather than developers having to handle it them selves explicitly for the sake of convenience.