> After you do that for a while, your program stops evolving as an expression of the problem being solved, because you've built it out of primitives that refer only to the internals of the program rather than to concepts drawn from the problem space.

Wow, nicely said.

You also remind me of the problem of removing "accidental duplication", or overfitting: this is when you factor out common code, but it turns out later that it's not really common - lots of minor and sometimes major distinctions occur as you implement more of the problem. It was only by accident that the code happened to be the identical at that stage of development. The theory constructed (the factoring out) gave too much weight to limited information (an early stage of the program), overfitting to that specific information. Generalizing from two instances is almost as bad generalizing from one. In your terms, it models the program not the problem.

It's so refreshing to hear similar thoughts to mine. :)