Hi
because a category of domain names is no longer available to register, particularly for any .whatever, does not give those domains within that category a value above the cost to register them.
many of these categories are highly speculative in nature, so "speculators/investors/ resellers and hopeful flippers", have consumed them in anticipation of demand.....which has yet to materialize.
the registries are the first to profit when a category is bought out.
imo.....