Having just come from working on my 'react' thread, I'm acutely aware of this. ^^; People will regularly try to just 'get things out of the way' by introducing all the major characters at once...without realizing that to a new reader who doesn't know this story, it's just a meaningless info-dump that they'll probably forget about in a few minutes, so they'll end up learning the character's names organically anyway. If they decide to stick around that long...
This is why I think it's better to start with just one or two characters at a time...readers will learn to care about the things that you signal to them to care about, by spending your time on them. Introduce 5 new people at once in rapid succession? The resulting message is that they are not important; that knowing who they are is incidental to the story and probably won't matter that much.
Spend a chapter exploring a character's thoughts and feelings? Use an existing character to introduce a new character by having them work together on the plot? That's when the reader gets the message that these are important people, because you're actually dedicating words and time within the story to showing who they are.
Technically no, but I think the readers still do need to care.
Like with all the comic-strip characters you mentioned: obviously, just from the way the stories are written; the authors don't expect you to have a deep emotional bond with them. They're just 'plucky heroes' for you to follow on fun adventures; as long as you care about what they'll do next and 'how are they gonna get outta this one', they serve their purpose.
On the other hand, in the case of something like Star Wars, I think that's less about emotional attachment not being necessary, and more about you finding your own way to enjoy the story regardless.
I don't care about Luke Skywalker either, and my response to that was simply having no interest in watching the original trilogy (even though I do like Vader). You decided to watch it despite that...but I don't think either of those was the intention. ^^;
With the amount of time they spend on Luke's character and adventures, clearly you are supposed to have at least some attachment to him, and you will probably enjoy the films more if you do. Instead of rating it a 7, for instance ("dull MC, but interesting setup with a great twist"), you might rate it a 9 ("great series, loved every minute; Luke is the best sci-fi hero of all time!").
Basically, if the intention is for the audience to be emotionally attached to the characters, then it kind of IS necessary for them to have that if you expect them to enjoy the story as it's written.
If they don't like Luke, but 75% of the movie is about Luke, they probably aren't enjoying 75% of the movie. They may still watch the movie and decide they like the movie, but their overall experience isn't as good as it could be.