If you're looking for a life partner then yes there needs to be a mutual attraction but aatraction goes far far deeper than looks.
What's the point in having someone who's pretty to look at but can't make you laugh, smile, someone you can talk to and all the things which are good :)
Beauty is in the eye of the beholder and everyone's different and likes different things. I used to go for extremely thin guys, including my ex fiancee. Many people though he was scawny and all that but to me he was the most gorgeous man i've ever met.
Often in chats with the girls when we confess to who we find attractive there's often a lot of different guys in there who aren't your convential good looking types, some because they make us laugh, the cute shy ones, the sweet kind ones, maybe just because there's something about them.
Grab a coffee someday and sit somewhere public and busy and just stop and take a look at all the couples going past and how different they all are.