I agree. But it can become a problem when sex is the most important if not the only reason you're in the relationship, and you develop deep feelings while your partner is only interested in the sex and your physical attractiveness.
Yeah, tell me about it, I spent most of 2005 & 2006 with a complete nympho and for some reason, while I was totally satisfied sexually I picked holes in other aspects of our relationship until we split up.
I then spent the next five years with someone I wasn't as sexually compatible with (well, the first few months were great but...) but for some reason I found myself letting her get away with being a total fucking bitch.
It's totally fucked up, when I was with a lovely, caring nympho I found myself super-critical of her flaws but when I was with a frigid control freak bitch I wasted five years of my life assuming the problems were all my fault.
Relationships are fucked up.