My gripe with tie in the OP was more of a issue of theory. I specifically avoided implementation issues (like speed).

To me, tie represents the ultimate in encapsulation. In theory, it is completely transparent after you've called tie (though as you mention, there are places where it's not transparent--these places should be considered bugs). It grates on me to see people treating tied hash lookups as if they were method calls, because you're willfully ignoring the reason for tie's existance. Speed is also a concern, but it would still annoy me even if it wasn't a factor.

A short tangent on Ruby: I haven't learned a lot of this language, but what little I studied teached me a few things. I used to wonder why the Java people were in such a huff over integers not being objects. Why would you want to extend the behavior of an integer? Ruby showed me why: it's so you can call operations directly on the datatype, and thus (as you noted) eliminates the need for tie.