You need to zoom out and look at things historically.
The result you see today is because of the choice of institutional building by the leadership after independence. They created a single civilian entity, the Defense Research and Development Organization (DRDO), in 1958 to oversee military-related research and development. The key word here is "civilian". The services role is very limited to provide support not more than that. If we compare it with USA, its a mix of Department of Defense Agencies like DARPA and Service Research Laboratories like
Air Force Research Laboratory (AFRL),
Naval Research Laboratory (NRL) etc. They work with defense contractors to prototype and build any weapon system.
Now, why do we have a design bureau for the navy but not for the air force? This is because of two reasons. First, there was no civilian entity that could perform that job. As for the air force, they had HAL, which had good enough design and development expertise. Secondly, it was within their reach. The air force cannot easily do that; the design and development of a fighter are far more challenging compared to a warship. Even in the USA, NRL was the pioneer in service-specific labs; every other lab came after. The inspiration of naval inhouse design was royal navy
Corps of Naval Constructors which overtime evolved into
Directorate of Naval Design (DND). It was a visionary decision for the navy to undertake. They had very small budget comparitivly so they had to make the most out of it.
At the same time, it is unfair to place blame on the air force and army because the design of our institutions was flawed. The innovation of the structure by the navy is an aberration, not the norm.
Services dont run development programs. They are just there to assist. They dont have any leverage over development of a project.
These responsibilities lie with either DRDO or the industry. Only with the recent DPP do we have involvement of services working with the industry as such.
No where in the world airforces design and develop platforms like you mentioned. Its out of their reach and mandate.
Services cannot directly fund projects under DRDO or DPSU like HAL. I don't know where these assumptions come from.
Correct, in my opinion, if DRDO had prioritized the testing infrastructure in the 1980s and 1990s, we could have been on a different trajectory. But again we were a poor country. We have a scarcity mindset. Why build an advanced wind tunnel for LCA or a high-altitude test facility for Kaveri when we can do it more cheaply outside?. We didnt plan for long term.
Also, as you pointed out, CEMILAC is another hurdle for the Air Force that naval platforms don't have to face.
Footnote:
During the time of Antony, there was an attempt to establish a civilian agency called the
National Institute for Research and Development in Defence Shipbuilding (NIRDESH) to reduce the workload of the Directorate of Naval Design (DND).