The last episode of "Tanked"...
You should have started your post with this, then I wouldn't have to had read the rest of it! Lol. But what do I know, I've lost a Torch, Frogspawn, and Oc. Clown in the last 6 months...
I think it's pretty well established that an "expert" can build a suitable environment specifically for a particular circumstance, i.e. shark tank, large pod environment for a mandarin, low flow tower for seahorses, etc., but for new aquarists that walk up and down the rows at the LFS and pick out what's "pretty," things can get hairy, or at least "EXPENSIVE," very quickly.
As far as leaving it in the ocean, I agree with the sharks, octopii, scorpions, rays. If you've had success in the past, good for you and better for the critter, but for every person that has had success, there are hundreds, if not thousands, that have had failures... and lots of dead critters.
Mac