Personal improvement, more career options, graduate education.... It is not all about the money.
Physical Therapists just moved from a Masters to a Doctorate degree without an increase in average pay and there are still waiting lists for PT schools.
At the hospital where I work all new grad RNs start out at the same pay rate regardless of ADN or BSN. Did I waste my time since I make the same as someone without a Bachelors and 2 years less of schooling?
As far as personal improvement, that's debatable. The Gen-Eds may have some benefit, but outside of maybe a foreign language course as a humanities elective, nothing else outside of the core curriculum will make me a more effective paramedic.
I can definitely see the benefit for career options, but that's typically outside of EMS. The EMS AAS degree still won't hold any additional benefit over just a cert at your current EMS job.
For Physical Therapist, I don't know why they're going for a Doctorate. Is it possible that the field is expanding, and the additional coursework is needed to address advances in that field? Do they desire more autonomy, or to protect their interests from other medical professionals? IDK
Your choice to go with the BSN helps you in two ways - a career ladder is available to you, when it wouldn't be had you went with the Associates, and there's a trend for hospitals to either require, or give hiring preference to BSN's. That's different than EMS, where a valid cert and experience are king.
It seems that those wanting educational advancements in EMS are generally seeking scope of practice, pay, and versatility that mid-level practitioners have. Do you think anyone would go to school to become a PA or NP if it paid $12 - $15/hr? I certainly wouldn't. But that's what EMS education advocates say that we must do in order to raise our pay, scope, and relevance in the medical community. I'm certainly not going to school for four years to make $40,000/yr working 48-56 hours a week. I'm going to go to PA school instead. See how that works?
There's an upper limit to what paramedics could do, and should be able to do in the field. After a point, you're trying to overlap with other medical professions. I could see the Advance Care Paramedic advocates looking to muscle in on nursing with home care, wellness checks, compliance with discharge care plans for frequent fliers and such. But, that's nursing! Same thing for ER Techs wanting to run codes and push meds in an ED. That's what a PA or nurse can do, respectively. IFT is more appropriately done by nurses that specialize in a particular type of transport, and respiratory more appropriately handled by a RRT. It would be overreaching to have a Bachelors paramedic that can do every type of IFT without needing a nurse or RRT.
I'm seeing an increasing trend of students taking the paramedic program through a college, but not doing the degree, just the core curriculum. The ones that go back for the degree, like myself, are generally doing it because it will help for a promotion somewhere down the line, or because the additional classes will apply to another medical degree, such as nursing.