Why didn't india send it's head of state? How about not wanting to bow down before the Chinese? Note how the Chinese have clubbed India along with Pakistan and Mongolia in the "Observer" status. Clearly indicating that the Chinese view India to be the equivalent of the traditional two countries that they routinely bully into doing their bidding: Pakistan and Mongilia.
If China grants India full status then we can talk about sending the head of state. Do you think the Chinese would send anyone if India created a Delhi Cooperation Council?