**WARNING! I am going to now make some broad generalizations about the industry that I have found to be generally true (although I have also found exceptions).**
Five or so years ago I think Rachel's argument would have been true and accepted. It was a marketplace where we were considered to be providing services. You were hired because you were considered the best, not the cheapest. But that was when everyone was busy, owners had money to spend, and not enough people to bid on their projects. All the numbers they got were higher and the rare low number was distrusted for its singularity. That meant the only way to choose who to hire was to look at other qualifications. They were buying our services.
Then came the market crash. Now owners had lots of people to choose from to spend the few dollars they were willing to part with. All of designers and contractors for hire promising the world and more at bargain prices. And everyone was willing to sign a contract that said just that. So now, no matter who they choose, they feel like they will be getting the same exact product. During this time period they were buying a commodity and it was during this time period that BIM gained the most ground in the industry ("...the world and more", remember). So that feeling has been generally inherited as it applies to BIM.
But now the market appears to be stabilizing and everyone wants to know what they should do about BIM. Should it be extra, should it not be extra? Should we charge more for BIM processes that really just make us better at our core processes? Shouldn't we charge more for BIM processes that really only enhance the product above and beyond what we would normally provide? What about the things that are above and beyond but still help us?
I don't know what the answer really is. Maybe the market will continue to pick the cheapest guy without concern for the consequences. Maybe everyone will work only in IPD so it is beneficial for everyone to integrate using BIM without charging more. Maybe owners will start buying services again and everyone will be able to flex their true BIM muscles. At the end of the day it will all be decided by the market and if it wants to buy services or commodities.