Why did the founders retain Slytherin's house?

[delwynmarch]

No: HPFGUIDX 117852


Hannah wrote :
"One of the most telling comments in canon for me, is in OotP (don't 
have copy on me for page number), when Hermione says it would be 
suspicious too many people from different houses were seen talking to
each other at dinner.  How very sad."

Del replies :
It's the whole concept of having to eat with your own House that I
find sad. Mealtimes should be perfect times for catching up with your
friends from other Houses. I know teenagers tend to be very clanish,
but the House system doesn't help them get out of that mentality.

I wonder how much the House system codifies the functioning of the
rest of the WW. Are we going to discover that some jobs are trusted by
people from such House, or that members of a same House keep banding
together in their workplace ?

Del