"Why would a superhero have a normal girl for a girlfriend? Why? Why would there be a Lois Lane for a Superman? Why wouldn't he be running around with Wonder Woman? She can match him! I mean, is there anything more insipid than seeing a character jumping from rooftop to rooftop, battling robots and monsters, deflecting bullets, flying into space, etc ... but when it comes to his love life he's just like us -- just another guy lying naked in bed ... why can't these characters be operatic in their relationships as they are in their battles?"
--Frank Miller, source unknown
Because there's more to romantic relationships and connections than similarities between two people. Clark loves Lois not because she can lift a car over her head or deflect a nuclear missile with a good, clean backhand. Quite the opposite, actually. Clark loves Lois because she has the spirit of a woman who can do those things and channels it through her abilities as a reporter and a writer. She's brave, intelligent, and feisty, but also affectionate and compassionate.
All the world is awed by Superman, but Superman is awed by Lois Lane. And while Wonder Woman certainly can relate to Superman's troubles more than Lois, Lois can relate to Clark's troubles and help him get through them.
Superman and Wonder Woman are good friends who do have an attraction to one another. Lois and Clark, though, are partners bonded together by love.