Let's stop using the word "filler" and instead of "filler saga" call Orange and BF "short sagas which came to exist in order to fill up time between the new generation region's end till the next generation start"
So... "short saga" is what I'll call them
They didn't HAVE to exist (unlike Kanto, Johto, Hoenn, Sinnoh, Isshu) and could not exist if the writers chose to extend Kanto and Hoenn instead
It doesn't mean they were bad sagas or that everything happened in them is "filler" or anything like that... just that it wasn't really necessary to have them and it's unlikely we'll get more sagas like these
So... "short saga" is what I'll call them
They didn't HAVE to exist (unlike Kanto, Johto, Hoenn, Sinnoh, Isshu) and could not exist if the writers chose to extend Kanto and Hoenn instead
It doesn't mean they were bad sagas or that everything happened in them is "filler" or anything like that... just that it wasn't really necessary to have them and it's unlikely we'll get more sagas like these