Given LN as the source, you'd find there's not much more there either. As extra you'd get Kyousuke's narration but that's about it. The anime's been pretty faithful to the source material with a few exceptions, and the so called 'filler' are simply self-contained events in the LN. There's rarely an overarching plot in slice of life shows and I don't believe it is necessary either. There's not a whole lot they can do with the number of episodes therefore it is natural that characters felt underdeveloped. But then again the 'developments' tend to be tid bits reader discover about characters.
To be honest the Kirino hate is amusing given the only difference between Kirino and Kuroneko is the latter has a more acceptable personality. Character development-wise Kirino has way more exposure (ep1-3, ep5-6, ep8) than Kuroneko (who was rather static since ep 2), we don't even know what drives Kuroneko to be the way she is. I guess many viewers just cannot seperate dislike of a character sterotype from the story telling.
Funnily a lot of the omitted scenes are about Manami. I'm not a Manami shipper but she's pretty essential in the novels to tie together many threads but not getting much love. Ep6 gets chosen in the anime because it's easy to animate but there are better choices development-wise.