Does prog have to be complex to be prog?

I agree. I can't think of "wonderous stories" or "I know what I like" as anything but prog and they aren't complex. I'm sure there are tons of other examples too.

I started this poll because I seem to keep hearing (mostly online) people say prog has to be complicated with odd time sigs to be prog. If that's the case then a lot of neo, prog folk, psych prog, post rock etc. aren't prog. A lot of stuff by Big Big Train is mostly just songs and not complex. If they aren't prog then what are they?

So complex equals good. Gotcha. 

I disagree. "Song-oriented"? Sure, but most of that are epic songs with many parts and quirks that go beyond typical song structures. Add to that the big instrumentation with flutes and violins, and everything is masterfully composed together in a truly symphonic way, just as Yes and Genesis did way back when. IMHO Big Big Train have been and still are doing a great job of keeping the true spirit of prog alive.

Case in point:

So for you it's all about the song structure. Verse, chorus song structure can't by definition be "prog." Is that it? What if there was a five minute instrumental section with a synth solo and or mellotron? I've heard stuff that was very simple sounding but had keyboad solos and a keyboard sound called prog probably because of the keys. Take the keys out and it's rock or maybe jam band or something else.