Fyri
Inkling
Mm! I think here we come to the situation that readers all come for their own reasons and desires. Is it important for a main character to be attractive?It's like a rich man putting himself in the shoes of a poor man when reading a book. It doesn't mentally affect him the same way it would someone who's struggled for money.
One angle is to say, yes-- if the reader wants to pretend to be the MC and visualize themselves as better than they are (a poor man imagining themselves rich).
Another angle is to say, no--if the reader wants to see themselves as they are as still worthy (and they don't imagine themselves as attractive).
There are many other angles to consider as well. Some people don't care about the MC at all and rather want to enjoy watching side characters.
Though, thinking about it, perhaps you have a point with the Twilight bland MC. I've also heard critique for Harry Potter this way (Shoot, was it earlier in this thread or on a podcast?). Beyond being "sassy" what was distinct about Harry? When I was in a college course that studied the books, no one identified with, nor chose Harry as their favorite character. And yet, the books soared in popularity. *Cringes at the notions this brings*
As it is art, perhaps everything and nothing is important, depending on how it is done and what the target audience needs.