well tell me what is the role intended for tejas in the first place
Mig-21 replacement, strictly speaking. It was not meant to be an "advanced version" of the mig-21 either. It was intended more like a desi version of the mig-21 and to demonstrate the capability of India to build its own aircraft. Unfortunately somewhere down the road it became a political ego and national pride issue.
You are right on Both counts
But Numbers ALSO matter
Even the most High tech planes have to spend a lot of time in HANGARS for Maintenance
Mig 21 is for Numbers
It take time to build planes ; they cannot be replaced overnight
China's aim is to have an ALL 4 Gen PLAAF by 2020
USAF will replace its older F 16 in a phased manner
First let them sort out their problems with F 35
It is better to have a Mig 21 doing Combat Air Patrol duty in the air
Otherwise if your skies are all clear then
EVEN a Transport plane like AN 32 will come and DROP
5 TONNES of explosives on your head
Numbers are not cheap.
An airforce is not always 100% ready. If any airforce, any airforce, in the world has 100 fighter jets then only 70 (maximum number) can be flown. And since this is the maximum possible number the more realistic scenario is only 50% jets would be war ready at any given time.
Planes need servicing and maintenance, for that they need spare parts and devoted mechanics working round the clock. That is why more experienced critics say that buying a 100 million dollar jet is easy, keeping the 100 million dollar jet flying is the expensive and harder part. Without supplies and spare parts an air force would be rusting on the ground.
Having numbers only would mean that finance which would have been otherwise dedicated to buying/making MKI spare parts will now also have to be diverted to LCA.
India should not take china as a role model and if they do then take it the full way. China makes her own weapons. It does not matter whether china begs/borrows/steals/copies foreign design. The thing is china makes everything on her own. India needs to do that as well.
USAF has problems with F-35 yes but they have a bidget of 700 billion dollars and multiple aeronautical companies. Even if F-35 is scrapped they will come up with another design. Their ultimate goal is an all stealth fighter air force.
What good is Mig-21 for CAP? That way you might as well have a armed drone flying in the sky.
IAF needs to induct quality instead of quantity. A 240 MKI + 240 Rafale air force would be far superior than having a 100 of every MKI, Rafale, Mig-21, LCA, mIG-27, Jaguar, Mig-29 etc.
In real war the aircraft other than MKI and Rafale would be useless. India does not have more than 55 Mirage which is too few.