That is very deep, Institches, and well said, though I'm also thinking that Neo has a point. Hmmmm, seems to me that "I love everything about you" is a wimpy way of saying "I love you", a kind of lead-up if you will, by someone who (I think) is a bit afraid to say the three little words even although s/he feels it. I also agree that those 3 little words are quite powerful, though I've heard numerous Europeans complain that we North Americans toss it around a bit too easily. Perhaps, a cultural thing, then?
As to the dating site commercial the OP heard the phrase in (yeah, I've seen that one on TV, too--it's over-kill adverts, I agree), I got the feeling that it's about the "compatibility" thing, being the angle that particular site is trying to push. Superficial you say? Probably. But then, ever tried speed-dating? Some cultures actually line up 5-minute meetings to determine compatibility among couples, where men bounce from table to table meeting a bunch of different women, in search of so-called true love; er ..... While there's such a thing as love at first sight, guess you might come to the conclusion that, after 5 minutes, you love (like? are attracted to?) everything about someone just met SO FAR, but not exactly would someone be "in" love, when break it down like that. Otherwise, culture comes into play, as well as maturity, etc. in which case saying "I love everything about you" could mean the same thing as "I love you" for some people, just a dash-around way of saying it, I guess.
Just my 2 cents.