If you've never played a Moog synth, it's difficult to understand what exactly this sound is. But it is real.
I agree- you have to play one to understand. But I'll try to explain it in words:
It's PERSONALITY. Bob Moog was a person, a gifted designer and he had a superb dialogue with the musicians he worked with. He knew how to make a synth musical. That's why people like Moog's so much, if it's a Bob Moog design, it's made primarily for musicians to play- issues such as cost, cosmetics and manufacturing challenges are secondary. There's real personality in the Bob Moog synths, and he passed that on to his employees also, which is why the Prodigy is so good, and the Little Phatty. All the great synths have personality- VCS3, Prophet 5, Elka Synthex etc. I'm excluding the Memorymoog and Polymoog, because Bob had little or no involvement in those, they were commitee designs.
OK, so you might not like the Moog sound. But his synths are always very musical, even down to the size of the knobs. It's very easy to get the sweet spots on a MiniMoog or a Voyager, for example.