Yeah, the first 3 games were (and still are) being updated. Still seems problematic to lose your original copyright before your even finished making your game. People looking to make a quick buck could put old copies of your game on Steam, same name and everything.

The Cave Story Steam version had some minor graphics changes but no major differences. Mainly, a lot of people hadn't heard of it before then, and people weren't necessarily aware there was a free version. Copyright was important here; without it, someone else would have put it on Steam years earlier.