houses and the sorting

[changelingdragon2003]

No: HPFGUIDX 89638

I'm new here, so I apologise if this has already been discussed. I 
did try to check that it hasn't.
I was thinking about the houses, and in the first book being sorted 
by personality seems a charming idea, but by book five it is starting 
to seem sinister and even the sorting hat is unhappy. The sorting 
certainly causes problems, mainly to do with rivalries. Gryffindor 
and Slytherin especially seem to be at each others throats. Some of 
the teachers seem to join in with this rivalry, notably Snape 
although even McGonnagal fails to give the Gryffindors homework when 
they have a quidditch match coming up, and that surely can't be a 
good thing. Even the DA has no Slytherin members, and I would have 
expected the Slytherins to be very interested in learning jinxes. I 
suppose they didn't want to join something Harry had started - or 
Hermione never told them about it. I do think the houses should learn 
to work together - surely all Slytherins can't be bad.
One thing I was wondering is why the founders thought it necessary to 
split the students in this manner, while alive they split them in to 
those they prefered to teach, but why carry it on once they are dead? 
Did they think it would be good for children to grow up close only to 
those who share their own strengths and weaknesses? If so I disagree.
Does anyone have any theories as to why the founders wanted things to 
continue in this manner?
I apologise for rambling.
Changeling.