I guess I fail to see how the GSL could address the fact that the changes were too radical.
Other than permitting a rollback.
Maybe you can explain a bit better by starting with your definition of "radical changes."
My definition includes both mechanics changes and IP changes.
Well so does mine. I'm not sure I can give you a concrete definition, because I think it's somewhat subjective. (Well maybe not the idea of radical change, but the acceptability of such change?)
But lets say a change like ditching skills like "craft."
Had the GSL been more accepted, you don't think there would have been some big names in there itching to put forth a new crafting system for people?
I'm not ignorant enough to say this would have solved everyone's problems, but I'm sure it would have helped.
Plus sometimes if people are making cool ideas for something, then it just makes people want to use the new idea despite the radical differences.
I think like it or not a lot of people are influenced by the actions of the "big names." If they aren't moving forward with the system because of the GSL, it doesn't matter if they still think the system is good or not, people only see that they're not moving forward with the new system.
I think if they did accept the GSL, and moved forward with producing stuff, more people would be switching. (Even if it's a subconcious sort of thing.)
Whehther or not this was anticipated by WoTC? I can't answer. Well I have thoughts, but I can't answer with authority.