I think theses look perfect. The 710, to me (and I think to Hayashi) must be a relaxed fit. Yes it's kind of slim, but you can have a slim and relaxed fit. That's the point of the 710 imo.
Why the 710 look so good on asian bodies and so slim on caucasian's ? Because as Hayashi said, it's 2 completely different body types. If you listen to Hayashi's advice for sizing, he said "take it snug because it will gain an inch", yes, but that's for an asian body. For a caucasian body I definitly think you should size up.
It looks good on asian bodies because they (usually) are skinny around the waist, the thigh, the butt and the legs (compare to us, caucasians). The result of that is some room left around the thigh and orevall around the legs, which gives it a delicious relaxed and vintage vibe, almost to a bootcut-vintage type of vibe.
(that's a woman though)
Of course, having a small waist will reinforce that, genetic is a thing, we all know that. But even with a larger waist you can get this type of vibe while sizing up and wearing it high on the waist.