Consumer confusion is exactly the reason that I think that studios should never, ever release SD material on Blu-ray. They can put warnings on the package and explanations at the beginning of the disc and there will still be people who buy it and wonder why a mid-80's sitcom still looks like crap when it's "high definition". In the minds of some consumers that would create or reinforce the idea that everything that isn't modern has no increase in resolution because it's "old".
I simply don't buy this point of view. The whole "consumer is too stupid" argument never made sense to me. To me, there are distinct advantages to Blu-ray that very few seem to be capitalizing upon, and storage capacity is one of them.
I'm not implying that studios need to go all out and start a "SD TV on Blu-ray" campaign with multiple shows, but how about one? Test the waters and see if it sells. How else is anyone going to know? Pick a very popular SD show from the 70s or 80s, put it on BRD and see what happens. I think people will recognize that there are many, many more shows per disc and make the connection. When people see the boxes next to one another on the shelf, it seems to me they'd prefer the smaller one. There should be a disclaimer about the source material, yes, but that's not a bad thing.
Convenience was one of the selling points of Blu-ray in years past, but it never seemed to come to fruition. Blu-ray is no more convenient than DVD, just clearer. Downloads and streaming are gaining more foothold. Why? Convenience.