I waffle back and forth about whether I want my teacher to give me advice on where to add rubato or dynamics or creative articulations. It seems that if it's not the organic decision of the player, it'll be mechanical musicality that has no real emotional connection. But then again sometimes I'm satisfied with the "musicality" of a piece which, to any audience, will have sounded very cold and boring. Any teachers out there have any ideas on the topic of teaching interpretations and musicality, beyond the mechanical and theoretical process of learning piano?

sorry for the double post, hit the "back" button on my browser and apparently the post got re-sent.

As a jazz pianist I still find it strange that there are such strict rules in classical music. But on the other hand, if Beethoven would have wanted you to make up your own interpretation he wouldn't have written fff or pp above the lines.
But to hopefully answer your question:
I think no one can teach you this. The first thing is that you can play the piece technically correct. Only then you can focus on interpretation.
Try to understand why there is a ~ or a < or a > or ^ or even a #. Most of the time it makes sense and once you understand it, you probably feel it too. Get into the music. Sounds like new age, but it's really not that hard. You just have to think by yourself "What's he trying to tell me with this?"
And if you disagree with the composer: he's probably dead so you can do your own thing without upsetting him.