Lackattack wrote: I didn't like the fact that anyone could block anyone for any reason.
Why?
This was for the best. You had no headaches and the only people affected were those who were ignored (and why would someone want to play where they're not wanted?)
Players used to be able to keep matters private. Now confrontations have to be aired publicly creating the inevitable slippery slope of retaliation and cross-denigration.
Also, more monitoring is necessary, greater adjudication required and the penalties (e.g. public humiliation) are steeper.
An e-bay style rating system might be good (although abuse is both possible and probable), but I can't imagine why you would want to commit your time and resources and those of the community to playing kindergarten cop.