Mahabharat is not only about Krishna and his philosophy, it gives you details about karma yog and Gyan marga (not only in Bhagwat gita but so many little stories where Krishna isnt even mentioned). Vishnu shahastranama a conversation between Bhisma and Youdhistir is also a small part of Mahabharat. like wise you will see post war gita- Anu gita and many other Gitas within the poem. Details of Raajdharma, patni, putra dharma, Raajneeti, economy and many many topics are covered in Mahabharat. other great topic im fond of is Vidur niti..i enjoy reading it which is also a part of mahabharat. so i dont think Mahabharat only describes Krishna's plot to kill Kauravas