My DCs were born in Japan and went to Japanese kindergarten/preschool so I had to do daily bento boxes. They are definitely the domain of the competitive mummy - some women really did get up at 5am to cook 3 individual broccoli florets, cut up sausages to look like octopuses and arrange bits of vegetable and seaweed on rice to look like cartoon faces. The rest of us just put whatever we could find in the fridge, or made use of the very handy frozen bento-sized portions of veg etc that you just put in the bento box frozen, and they'd be thawed and edible by lunchtime....
We are now back in the UK and (somewhat unfortunately) DD has retained her Japanese tastes and still won't eat sandwiches, so I often do rice-based lunchboxes for her, but these days it's usually some kind of sushi roll or stuffed rice ball, as they are quick to make* and easy to eat with your hands. I do sometimes do the whole bento thing, as she likes having the box and the chopsticks etc. No cartoon faces though.
For a while she (and DS) didn't want bento, as I think they got teased by other children at school, but it doesn't seem to be a problem any more - I think it might be the Yo Sushi effect, most of their friends have eaten things wrapped in seaweed and so on now.
(* probably only easy if you have an automatic rice cooker with a timer, so you set it the night before and wake up to perfectly cooked rice - it's also DD's favourite breakfast food)