The group learns to grow up in various pairings and ways. It seems to be generally disliked because of the annoying children, but them being annoying is kind of the point.
Because the point is that tropes exist for a reason - they're aspects of fiction that have been tried and tested and can work when utilised well. Trying to deal with the bullying cool kids, doing stereotpyical US collegey stuff, hatching ridiculous revenge plots, two characters feuding before bonding at the end, et cetera. The writers are basically saying "yes, we know, Simpsons did it". You can't always be original.
Because the point is that tropes exist for a reason - they're aspects of fiction that have been tried and tested and can work when utilised well. Trying to deal with the bullying cool kids, doing stereotpyical US collegey stuff, hatching ridiculous revenge plots, two characters feuding before bonding at the end, et cetera. The writers are basically saying "yes, we know, Simpsons did it". You can't always be original.