There's nothing wrong with producing commercial software for Rails, I
doubt you'll find many mac users on this list who haven't purchased
themselves a copy of Textmate. The key change in philosophy though is
that any software has to pass the value test. Gone are the days when
large companies footed the bill for expensive software licenses.
Many Rails developers work for small independent companies or startups
so Applications like Textmate which provide excellent productivity
improvements for modest investment are successful, whereas bloated,
expensive applications will most likeley not be.