How we see it, we buy what we buy from who we choose, and deploying those systems in the most effective way to protect our interests. Tactical systems have traditionally been deployed against Pakistan because it has been a de facto military state for most of its existence. Strategic systems against China because of the asymmetry. Strategic systems like long-range missile systems are deployed against china as a deterrent in the case of stuff spills over. Given the terrain between India and china, it doesn't mandate a large deployment of tactical systems like Arty and infantry. Whereas against Pakistan, given the history of expeditionary exploits of PA, and terrain favoring conventional warfare, Arty, Infantry mech, and armor can be deployed against PA.
In addition, we can afford to pressurize Pakistan into a pseudo-arms race but we cant do that with china. So most bang for the buck is to deploy tactical systems we buy against Pakistan rather than china.
But you often seem to ignore India's firm stand towards its own interests, remember we took on Pakistan and china during the cold war, one an ally of the US and the other an ally of the soviets.