That's easy to explain. I have the Spirit CC, so my points never expire. I can pick up a flight for 2500 points plus very little money - heck, even "upgrade" to big front for under $100. Southwest is no longer a discount carrier; WN's pricing has gone through the roof. Spirit is the el-cheapo.

The only risk to flying Spirit (as I have previously mentioned) is that you are never quite sure the flight will actually take off. Now, I can use the Spirit-WN backup strategy and if I run into problems, the most I will be delayed is one day. Great new strategy that I learned right here on FT!