I haven't read the full thread (forgive me), but I get the gist of much of it. My opinion, fo what it's worth:
1) Insta-buddies (I used to call them pickup buddies..you pick them up are the boat) can be worse than diving alone. They may be poorly trained or experienced or simply have bad buddy skills. I'd rather an insta-buddy say "I'll see you on the hang line when it's over" than to go through the motions and force me to shorten or screw up a dive because if I'm their "real" buddy, I have an obligation to be just that....
2) To dive with a good buddy is the best way to dive. Period. Not only do you have someone to provide a safety backup, you have someone to back up your outrageous stories (a good one will lie with you....uh...that didn't sound right, but you know what I mean...they'd help you fabricate the details...)
3) There are places and times when solo diving is okay. Diving w/o a pony (a nice size one), diving after only 20 OW dives or diving when conditions are deep or dark or swift is not the time or the place.
I used to dive solo a lot. Mostly, it was because I couldn't find a reliable buddy and I felt the conditions reduced the risks (<70', shore dives, w/ spare air and gear in an area I was familiar with....) I like it because I was able to concentrate on my photography and not a buddy (like my brother, god-luv-'em, who always disappears into the gloom, kicking like "Loyt Britches" and forces me to chase after....).
Now that I have my son as a buddy (darn good one), I feel much better. Solo diving may be "safe enough", but you need to be able to manage the increased risk...and the risk is increased, if only incrementally.)