I'm not solo certified but after going through these posts I'm not sure it's worth it. It seems like even with certification it's still not as accepted that it should be.
Midwesterndvr:
Speaking from a place of not knowing that well either (pretty limited experience here also, and maybe only a bit over half of it "self-guided" (I don't think herd dives should count)), but having looked into it a bit deeper maybe - for reasons - I can tell you why I went for the solo Cert. anyway. I am not claiming that will apply to you or may help you with your decision, but I know your "Dilemma" because I've been there - so, maybe this does help:
On the one hand:
Yes. it seems like you cannot dive solo in many places under commercial control (or under government control, like some state parks apparently in FL) even with the cert. - period. It should also not come as a surprise to you that some boat captains or operators or even dive shop operators may want to know you first or at least have a talk and a good look at your logbook to see if they desire to take the chance of all that comes with and after should one one of their customers have an accident - even so there is a solo cert. A diver with a fresh solo cert. card and a total of 110 or so coral sea warm water dives may not mean much to a boat captain in a murky, cold, high current North Atlantic locale... and that's a good thing. And some captains or operators may just not want to go there - period. It's their business, their livelihood, and their decision.
In our area (I'm in your neck of the woods) the only Quarry I know of that allows solo diving with the "magic of the card is Haigh. - E.g. Pearl Lake and Mermet Springs do not. So that's one side of the coin for me ... a bit of a limited local opportunuty to "use the card" .
The other side:
Well, once I get colder water gear I will try some Lake Michigan Charters, won't mind being insta-buddied and go from there deciding if I even like that diving... I do however prefer self guided exploratory diving... (have a suitable kayak too - but as far as Lake Michigan is concerned, except for a few near shore sites on a really nice, calm day, I am not judging myself as ready to kayak dive there yet - working on it...) Solo diving is easily done e.g. on Bonaire so, . Until I judge myself ready for a local LM solo dive, I can practice what ever I want at Haigh even when my usual buddy is not available (which is most of the time... conflicting schedules). I won't bother anyone if I rather try to get a better picture of something for 10 minutes instead of a more tolerable half minute. And of course, next chance for a dive vacation hopefully will lead me to a destination where I can do maybe a couple dives with my buddy (who then likely had enough for the day) and one or two more by myself ... immersing my self in whatever I want to be busy with no matter how boring that might be to someone else...
Of course liking to take pictures is putting me in a situation where I am, while trying not to, always at danger of being a horrible dive buddy. I am compromising what I want to do and my buddy has to wait around for me - or be himself the horrible same ocean buddy... So, realistically, I was already solo diving a bunch anyway... might as well do it right. And then, once I (periodically) got the urge to spent infinite amounts of time on one silly picture out of my system on a solo dive, I like will be a better buddy for the buddy dives on the trip too... - a good thing in general, more so yet if your buddy is your underage son...
That or something like it went my thoughts. Then of course I also had a cert that sort of taught the same mindset... (Fundamentals of Tech) - but that "route" does not count as a license to dive solo where the solo cert card wants to be seen... So on the surface the actual solo class was (in comparison) a bit of a let down to me. But it produced the cert. Should I maybe have put the money towards cold water gear instead? Maybe. But, come time, come gear - that sort of can't be helped I think (is there a T-shirt yet) .. I can use the solo card in warm water where I won't ever bring the cold water gear when I have it... and thyere was a class when i happened to have time ... so I took it... As someone already put it I think - the card is no good where it's no good. Where it is good it helps to reduce drama (for a rental pony or gas or the shepherding DM on the boat or...)...
For fully self supplied, fully self organised fully self traveled/ walked / boated / paddled to dive adventures ... I don't think the license was a legal necessity for that actually - but I really don't know - but now that I have the Cert. I can stop wondering and just worry about the diving, the fun stuff ... do what (after research), on the right day / night in the right conditions I find I dare to safely do...
In short: I think it broadens my options to actually go diving in a busy and time constrained life and that's why I went for it. I'll find out sooner or later if that holds up in reality - and I'll have fun in finding out....
But even if not: Because I went for it, I had to think about it. Refresh some stuff, do some dives, get tested and questioned think a little more about it... and you see, it involved diving... so I had fun doing it... and I may even have learnt something... so, how bad can it be... Done. Now I get to use it. Good!
For what it's worth, the "done" part and the "get to use it" part feels good! Who cares if it really makes sense to have gone for it? But I think in my case it will indeed make sense, just for "picture taking reasons alone" (not good enough yet to call it "photography"...) So below the surface (so to speak), that class then was not really a letdown for me. It was good - and it keeps "feeling that way" - if that makes any sense. I do not regret having spend the money or the time on it at all.