An airline where "bags travel free" is another way of saying if you don't use your luggage allotment you're subsidizing other passengers. The lowest fare option should always be al-a-carte. And Southwest will no doubt continue to include a bag on any premium service.
That's just like, your opinion, man.
I book trips well in advance and am not always sure if I'll need to check a bag. I'll carry on if I can after having lots of lost/delayed luggage experiences. Sometimes I have something that is not allowed in a carry on, and sometimes various sports equipment takes too much room to fit in carry on.
I don't know that I've ever needed both checked bags, yet I still leaned towards Southwest when booking. Subsidizing others, I guess. I'm happy with a base fare including some things I may or may not use for the peace of mind of not worrying about it later. The fee-for-everything-we-can-think-of model adds stress and requires more planning.
It's unfortunate that is what air travel has become. What used to be a fun part of a trip in its own right is now just a hassle to deal with on both ends that you hope does ruin the rest of the trip. And it is why I end up driving most trips that are under ~8 hours in the car.