I'm no expert on the programmes, but think of it this way - WR is a no-tiers points accumulation programme; when staying at Wyndham Hotels (and not Super 8, Day Inns or anywhere else in the extended group) this particular property brand recognises return visitors with a few useful perks. You still get your WR points though.
I agree - it does seem really odd to have a differentiation, especially as the differences don't appear to be enormous.
Mind you, Interconti have their Ambassadors as well as Priority Club, so the model must work in some circumstances.
I expect Wyndham Rewards may be able to illuminate...