Oh I know exactly what you mean. It's a boxing thing yes. I'm also inspired by the old timers and the ones that still do that. It's a pros and cons thing. The reason why I like doing it is because it's a good defensive position. My head is harder to reach as it's further away, and it's easier for me to see shots coming and react. Also it's harder for anyone to land body hooks as well. What I really like about it though is that it's easy to manipulate distance while still being in range to strike. You appear much further away than you really are, and as soon as you shift your weight forward you can hit them back. Or with your head a little forward, you can pull back slightly and not get hit.
I was using it too much before, kinda like Machida you posted who ALWAYS stays with his weight back (the boxers don't do that), but mixing it up with having your weight forward at times, going off the centerline and crouching more I feel makes it more adaptable. Never had any problems with being sweeped or pushed around in KB/MT sparring, usually I'm the one who push people around, but then again I haven't sparred any high level MT fighter with good sweeps. I'd be put on my ass for sure either way.
In my mind a good stance is one that a) suits the person and fits their strengths. Not everyone should have the exact same stance, and b) one that is fluid and can adapt to the ruleset, and opponent. Like if I was fighting a good wrestler I'd lower my center of gravity more, exactly like Rory is doing in the picture with Woodley. There's downsides to that too like them faking the shot and finding your face with the uppercut or knee more easily, but there will always be pros and cons.
Thanks for the reply, I think it comes down to styles a little bit, but I will get what you're saying. At some point soon I'd like to start practicing MT for real and then I might have to change things up. Then I'd really have to pick your brain about how to set everything up!
EDIT: Nice article btw!