Shakespeare and the L-Word

Vonnegut said that everything in a story should contribute either to the plot or to characterization.  With respect to the better craftsman, I wonder if he's going far enough.  Take Wild Bill Shakespeare.  How many words will he expend, say, on pure characterization?  As far as I can tell, none.  A woman in love with a man, seems an obvious and worthwhile bit of characterization.  Is it permissable for a writer to let a wife say she loves her husband, purely by way of establishing the relationship?  In Shakespeare, plenty of women tell men they love them, in plenty of different ways, but there's always something else at stake.  They never say "I love you," unless they want something in return.  (Much like real life in that way.)  The L-Word in Shakespeare always comes with fine print - a "therefore."
Juliet: I love you; therefore let's defy both our families and get secretly married.
Desdemona: I love you; therefore, please don't kill me because I swear I'm innocent of anything you think I might have done and later you'll hate yourself for it, I guarantee.
Lady Macbeth: I love you; therefore, you need to quite shilly-shallying and go kill Duncan because we won't ever get a sweeter opportunity than this if you ever want to be king of Scotland.
Portia: (In Julius Caesar, not Merchant of Venice) I love you; therefore, you need to spill the beans about what's been eating you, which I'd never say out loud, but I'm pretty sure you plan to ill-kay Aesar-Say, which you'll never get away with not in a million years, so think about it.

And men tell women they love them as well.
Richard: I love you; therefore, you should marry me, even though I'm physically repulsive and I killed your husband, whose body is right there in the coffin next to you, but in any case, I only killed him because I love you, as I already explained, and you should on no account suspect this is just a Machiavellian tactic on my part to bring me one step closer to the throne in a diabolical plot that will ultimately result in the deaths of almost the entire York family paving the way for someone named Henry whom no one has ever heard of until now.
These of course, are not actual lines, but generous paraphrases on my part.
It's not for nothing that the greatest writer in the English language was a dramatist.  He knew if you really want to sell the popcorn, it's not enough for people to love each other.  Stuff has to happen.