I have been thinking about this since the last chaos codex. Can someone explain to me why chaos is not totally superior to their loyalist brethern?

Chaos pros:

-Bolt pistol, close combat weapon and frag grenades on everyone
-Leadership 9, partially offset by their lack of "and the shall know no fear, but on the other hand the most annoying units are fearless anyway
-Marks, some of which are awesome
-Obliterators
-Terminators that can have a mix of power weaponry, and combi weapons as well
-Demon princes
-Better pyschic powers, especially the lash
-Demons
-Better basic commander

Loyalists:

-Chaplains
-Land speeders
-Whirlwinds
-Assault cannons
-Scouts
-More bling bling for heroes

This does not bother me that much because I play Tau, but I was thinking of building a marine army some time in the future. But when chaos seems so superior, it just seems less fun.