I do agree, I don't know why people are bothered that Winky and SPEW are left out of GOF when neither have any real bearing on the whole story (and when i say that i mean all the books together). She helped Barty Crouch Jr in GOF yes but spending time introducing her and explaining her would take up valuable time needed for the more important characters!
I would say though, that some things when added in are handled badly. For example i think they kept everything that needed to be in OOTP which is great, but occulmency and Harry-Cho were skimmed over rather than having the time dedicated to them that they needed to get the point across. They may as well have cut the Harry-Cho romance for all the impact it had in the film. The director and Warners were obsessed with getting the film in at 2 hrs 20 mins with that one and they really should have just let it run for another 20mins. I really hope they don't let that happen again because i think as it was OOTP was a decent film but with a bit more time spent on these things it could have been brilliant.
And can I just add I understand why they're having Lucius and Tom Riddle at school together, it makes sense as the actors portraying them are of a similar age, explains a connection between them without need for exposition and in general is just good streamlining of the story (and it's the story that is important, not necessarily the plot).