I used to think like that, and still do for most stuff you mentioned, but have come around to the "one freebie physical a year" thing being worthwhile. Millcreek and Neemi and BobR and others can weigh in, but there is probably both a health and cost benefit to insurance providing a free annual physical, including bloodwork at free or minimal cost to catch issues that could turn bad (and expensive) if not caught and treated early. Insurance companies could still offer cheaper catastrophic insurance that also includes the once per year checkup, with the client still paying for other routine doctor visits out of pocket (all expenses to be tax deduction eligible).
Heck, even at my age, with my current good health I would opt for catastrophic that included an annual checkup. I already have about the minimum bronze plan (with HSA) that ACA allows, but that's costing me $480/mo for services I don't use. I'm basically paying nearly $6000/yr for my doctor to stick her finger up my butt once a year.
I don't know the exact numbers as far as the health costs/benefits... but I do know that it's been repeatedly shown that preventative care is several magnitudes cheaper than emergency care.
For example, I know that my middle child's last "well child" ("free" yearly visit) cost my insurance about $500 - but that included all of his school shots.
On the other hand, I remember a kiddo that came into the ER for a "rash" that ended up being measles. It ended up in a hospital admission, tons of expensive IV-based medications being administered, and then we had to clean any and everything that was exposed to that kid by basically dumping it in bleach for several hours. The ER room that kid used? Out of commission for 4 hours while it got bleach-cleaned. And that was on a busy night, so we really could have used that room to help treat other patients. And that kid would have to be in a private room - during a busy winter season when most hospital rooms were double bunked. Total cost of that? Not exactly sure, but it's a whole lot more than $500. That could've been prevented had 1. the parent had a clue that vaccinations weren't evil and 2. they'd gone to well-child checkups in the first place so that their doctor could educate them about issue #1.
So yeah, I'm a fan of the once-a-year physicals idea of the ACA. I think it's something that ought to be included somehow - I don't know how exactly. Maybe as a "you must be this tall" sort of requirement to be an insurance agency.
Another issue that needs to be addressed is the whole medicare/medicaid copay tier system. I've had several patients check into the Emergency Department because they couldn't afford their copay at the doctor's office - a whole $10. But the $0 copay at the ER they could afford. One of them was checking a newborn in for constipation - baby hadn't pooped in 2-3 days (not a big deal). After checking a rectal temperature, the baby pooped. And they insisted on seeing the doctor anyway "because we're already here anyway!" I know they the existing copay scheme is so that there are no barriers to emergency care, but there's already a law about that (EMTALA). The copay tier system is just the first line of things that need to be reworked.
I'd also like to keep the "no pre-existing conditions" clause of the ACA - I saw so many people who lived in pain and were just building towards an expensive breaking point because of prohibitive insurance costs. When in reality, their chronic diseases are easily managed with a couple of relatively inexpensive daily medications. Again, prevention is magnitudes cheaper than emergency care.
And while we're dreaming, I'd love it if vaccines weren't so optional. Spread 'em out? Sure. Skip 'em? Not unless you're *actually* allergic or severely immunocompromised.
Again, I don't have specific numbers on this - but a nurse can dream, right?