Instead of re-inventing the wheel why not buy some of the BrahMos missiles from India or the Hae Sung missiles from South Korea? It will upgrade our weapons system without the time and expense of R&D.
Because then we are at the mercy of a foreign entity for our supply of a critical weapon.
The Brahmos is only half-Indian; it can’t be exported without Russian consent. Besides, it’s size (3+ tonnes) is not exactly an advantage.
The Hae Sung missile can be considered to be in the same league as the Harpoon Block-2 (medium size/range and sub-sonic).