I flew WN to LAS earlier this year - it just priced out much cheaper, and that was the biggest factor for me! I made the mistake of flying UA to SAN for Labor Day wkend earlier this year. I live in the East Bay, so getting to SFO for the non-stop was kind of a pain. I did not fly OAK-LAX-SAN because the connection times with UX are terrible ex-OAK-LAX. Anyway, SFO-SAN, a little more expensive than WN, but I am like you: want to maintain program loyalty for status. But after all the hassle of getting to SFO and back...I thought to myself: is 1000 EQM's really worth all this?
Upon further review, it isn't to me. So, I guess the next time I fly to a dest. where the options from OAK are better (and cheaper!) I'm flying whatever that carrier is ex-OAK.