I think that Emma Thompson-scripted S and S was very clever in how it tweaked (via casting and editing, mostly) the novel into something more immediately palatable to contemporary filmgoers.
The novel doesn't think Elinor's 'sense', discretion, rational realism etc about society needs to change at all, but Marianne's romanticism needs to be pruned - her 'sensibility' needs to change into 'sense'. JA approvingly shows Marianne becoming more like Elinor, so only one of the sisters has to change.
Whereas modern film audiences would find JA's Elinor far too buttoned-up, prudent and old before her time for their taste, and probably find a moody, passionate teenager like Marianne easier to relate to. And another 'problem' with the novel is that neither of the men they end up marrying constitutes a bona fide romantic hero. The novel's Edward Ferrars is shy and dull, Brandon is a middle-aged man only just younger than the girls' mother, who wears flannel waistcoats (the contemporary equivalent of a Zimmer frame
).
So the film tweaks things slightly by making Elinor's hysterical tears when she hears Edward Ferrars isn't married to Lucy Steele the emotional heart of the end of the film - it's suggesting she has spent the action of the film being overly repressed (so we're encouraged to agree with Marianne when she asks E 'Where is your heart?' rather than thinking that E's behaviour throughout is perfect.) Plus casting Hugh Grant to do his (for some people, at least!) likeably diffident mumbling toff thing makes his appeal more obvious, especially in how he relates to the film's tomboyish Margaret. So Elinor is humanised (by contemporary standards) by the film.
And casting Alan Rickman as a brooding, sexy Brandon makes Marianne's 'punishment' for her extreme sensibility/imprudence far less extreme than it is in the novel, where he's a more obviously 'safe' second best.
So Marianne is blamed less for her conduct in the film and Elinor is made somewhat less starchy - both of them change, not just Marianne. It's more about finding a balance then the necessity for sensibility to change into sense, if that makes sense?