Yeah, the ripped like a maniac thing is fairly new, but if you look at Luthor: Evil Genius (1941), Superman had a clearly defined body shape. And both Reeve and Cain were in good shape, but they weren't in Superman shape. He was, like you said, thick. So far they haven't gotten anyone that's got the chest/arm proportions of Superman, and I know people like that exist because I've seen them. That's one of my main things, is most of these guys have arms that are smallish in ration to their breadth and depth.
Also, diving suits give more definition than spandex, but although I like the look, it's not really what I mean, it's just the size/depth issue. Clark is a big guy.
So I'm not really looking for a comic book Superman as an Alex Ross Superman.
Watch the Lois&Clark pilate, part 2. You see Dean Cain for a few minutes with his shirt off, and he really *is* in Superman shape - I'm serious, he was *way* more muscular than that costume made him look. I think Nightwing was right, on this one.