Side characters being unimportant isn't usually the root cause of people's problems, it's when the side characters take up too much time for the value they bring to the series.
If you devote too much screentime to a side character and they don't end up mattering in the grand scheme of things, that time feels wasted and like padding/filler.
There are lots of shows that do side characters well because they don't spend a second more on them than they have to - they set them up, deliver their value to the story, then die or fade into the background until they're needed again. But when you have entire stretches of episodes dedicated to side characters fighting between each other or getting up to wacky hijinks only for them to end up playing a tiny (or nonexistent) part in the overarching story, it's a pacing and expectations issue and is bad writing. If you devote time to a character, people WILL get attached to them, and if that attachment is betrayed, it's the writer's fault. Do not let people get attached to characters if you intend to forget about them. Do not spend massive amounts of screentime on characters that you (the writer) do not care about or have a plan for.
There are people who get overly attached to characters in a way that is totally beyond the writer's control, but these are the vast minority of people. Most criticism of bad side characters is entirely valid.
If you devote too much screentime to a side character and they don't end up mattering in the grand scheme of things, that time feels wasted and like padding/filler.
There are lots of shows that do side characters well because they don't spend a second more on them than they have to - they set them up, deliver their value to the story, then die or fade into the background until they're needed again. But when you have entire stretches of episodes dedicated to side characters fighting between each other or getting up to wacky hijinks only for them to end up playing a tiny (or nonexistent) part in the overarching story, it's a pacing and expectations issue and is bad writing. If you devote time to a character, people WILL get attached to them, and if that attachment is betrayed, it's the writer's fault. Do not let people get attached to characters if you intend to forget about them. Do not spend massive amounts of screentime on characters that you (the writer) do not care about or have a plan for.
There are people who get overly attached to characters in a way that is totally beyond the writer's control, but these are the vast minority of people. Most criticism of bad side characters is entirely valid.
