Wanna Get Away Plus: Southwest's Newest Fare Type

I love Southwest and we fly them almost exclusively. But I don't see much benefit from this new fare option over Wanna Get Away. Appears that the only difference is that you can make same-day flight changes. I could see that being desirable for business travelers, but business travelers will probably book a higher fare class anyway. For leisure travelers it's not often that plans would change where a different flight on the same day is needed.

Currently there are a limited number of Wanna Get Away seats available for a given flight. When those are sold you must book a higher fare class. With the new fare will Southwest reduce the number of Wanna Get Away seats on a flight in order to offer the new fare? If so then the new fare will have the overall effect of causing people to have to pay more.

Hopefully there will be the same number of seats allocated to both of the Wanna Get Away fare classes, and the passenger just selects which option they prefer.