American Fan:
After rewatching Oxygen (most of it anyway) I had to downgrade my rating
Hmm, and I thought we were so perfectly aligned. At least this will quell any rumours that you're my secret alt account. Haha.
I think even loyal fans of "Oxygen" and Supanut (like me) will agree that this series has some weaknesses and that the third storyline is the big weakness. When I rewatch it, I always skip over the doctors (although actually, I think Khim is a sweet character, and I find her fujoshi obsession - minus the doctors - rather funny). As to Supanut being "stiff", that's a fair criticism that many make - but aside from this being his first substantive acting role, one can also rationalise this as being Solo's character, i.e. Supanut is playing the role.
So basically, I don't disagree with your two main criticisms - but I love the series (minus the third storyline) nonetheless. As with a number of other series that I especially like, I can overlook the weaknesses (some quite glaring) because of all that's good - which in the case of "Oxygen" is first and foremost the lead couple: Gui's unfailing kindness and strength, Solo's quiet "lost puppy" nature and powerful bond with Gui. I don't need a lot of snogging or "steam" (which there isn't) to feel their intimacy. Needless to say, their physical beauty doesn't hurt either.