It is well known that changing domains is both technically expensive and harmful to am entity's presence online. Going from .org to .net comes with huge losses to the consistency of data across web services, (forums linking to nonprofit.org websites now may get redirected to something else if the non profit loses ownership of the domain due to cost.) This makes this situation a monopoly, which will be given the opportunity to take advantage of organizations who do not have a webmaster on staff. It's not about "freedom" of choice, it's about ensuring stability of costs for organizations.