Good observation that cromo frames started appearing in just-above-bottom-level bikes in the 80's. However, they were about as heavy as bottom rank bikes, so the advantage seems questionable. Take something with the same strength-to-weight ratio as cheap stuff, and use the same amount of it. What's the result? I think it's something that's stronger than a cheap frame, but in general, the cheap frame was strong enough. So I think most of what it gives you is bragging rights.

T-Mar, please write a book! It's great to read this stuff.