Ambiguity seems to be Disney's specialty. You have that ambiguity in the Membership Extras Statement that could be construed to mean that effective 4/4/16, anyone who has purchased only resale, incuding prior purchasers, would lose the benefits. That same document initially defines "Members" as only those who buy directly from Disney, but then says "Members" who do not buy directly from Disney do not get the benefits, i.e., a contradiction in terms. Nevertheless, the statement on the site and the actual letter from Potrock said that all those who purchased pre-4/4/16, regardless of whether they purchased from Disney or resale, will be entitled to the applicable benefits now being excluded for new purchasers.
As to how bad the loss, we still have the 25 point add-on issue. It appears that a new resale purchaser can overcome any issues by simply adding on 25 points through Disney. That may be all that Disney wanted to accomplish but we need to see if any other restrictions will be announced. It may make sense to allow even just the add-on purchaser to get the extras because most of them -- e.g., merchandise discount, AP discounts, TIW, dining discount -- are profit makers for Disney both in their sale to and use by the member, and keeping members on site to otherwise spend more money.
I do not consider this a change anyone should be happy with. Every member may someday be a seller and this lowers the resale value, and thus every member is impacted negatively.