The reason is simple- time. The first P-17A will ony be in service from 2022, these Project 1135.6 frigates will all be in service by 2021. The P-17As wil surely be far more advanced but the IN cannot afford to ease up on their expansion plans, numbers and timelines are also important.
200+ Helos (NMRH and NLUH) for the IN had better be part of this shopping list bro, inexplicably this area is being entirely neglected.
PHALCONs? 2 more units are currently on order for the IAF (for a total fleet of 5) more orders may come in the future.
Spike SR is in service with Indian SOF.
Spyder SR is already in service with the IAF and IA.
Will be intergrated on the IAF's Rafales and Mirage-2000s (maybe even Super MKIs), perhaps the SPICE 250 will be seen on the LCA in the future.
The LITENING LDP is the standard LDP of the Indian Air Force and Navy and they will constantly be ordering more as their fleets expand. Just recently the IAF ordered 164 of the G4s.