Your second line is simply not true. Both American [1] and United [2] have committed to waiving change fees if you don't want to fly on a 737 MAX. Southwest is farther away from bringing the MAX back into service, so they have less detail on their site [3], but it sounds like they'll do something similar.
[1] https://www.aa.com/i18n/travel-info/737-MAX-return-to-servic...
[2] https://www.united.com/ual/en/us/fly/travel/inflight/aircraf... (under "What if I don't want to fly on a MAX?")
[3] https://www.southwest.com/737-max/#return-to-service-plan (under "What are Customers' options if they don't want to fly on a 737 MAX?")