It's not up to Valve to create leverage, it's up to other companies to do that. Maybe GoG or GmG or EA or one of the thousand other people will create competition. But that's not a knock against valve, that's a knock against everyone else
It may actually
be in Valve's best (especially long-term) interests to get better compensation percentages for modders. They certainly do have significant leverage now that they are the ultra dominate PC distribution platform. But they don't view that as an issue at the moment unless modders make it one.
To further clarify my stance on the issue. I like the idea of paying modders for good work, but I hate the idea the 75% of my money will go towards someone else who had little to do with the work they created. I will also admit that I don't know what standard rates for a similar circumstance might be in other industries. I don't have any experience or knowledge and would love someone with some expertise to compare it. As of now I know the rates for the Apple and Android stores, and they come nowhere near this.
Above all, my sticking point is;
1.) The 75% Rate
2.) The incentive created, especially at these rates, to let modders fix issues with the final product.
I don't have a significant problem, other then the unknowns of what may happen (which applies to any new frontier), then these two points. I'm not a knee-jerk "mob" member as some posters are trying to make swathes of the community out to be. I'm attempting to have the best interests of both the modders, community, and developer in mind.