Very few actually have a degree requirement. But the gap between "minimums to apply" and "competitive" is normally quite large. They publish very low minimums (ex. HS Grad, 2000TT, 1000 turbine) just in case they want to hire some specific person due to connections/affirmative action. The vast majority of pilots will need much more than the minimums.

Also...there are not a lot of pilots applying to majors without a degree. They're not going to open up a vast pool of untapped talent by dropping the degree requirement, other than maybe the 91/135 pool. But I suspect they'd rather accelerate college grads flowing through the regionals before they scrape the bottom of the GA barrel.