Bad example. Flanker program was a very successful one. Later iterations came into being after a large number of Su-27 entered into service. This is not the case with LCA.
Successful or not the point was evolution which is necessary to develop futuristic technologies.
Russia even developed SU-35 when it was already test flying PAK FA and when its primary adversary was flying two types of 5 th gen fighter. China is inducting SU-35 when its J-20 is also entering service. The point is there has been always a neccecity for bridging programs between two generations
You are talking about subsystems. You don't a new air frame for that. That is not how this works. Mk2 is not a low risk program as you put it. It is a completely new air frame with completely new propulsion and will share very parts with Mk1.
Of course, you need evolving platforms for evolving subsystems. Capital assets are the primary driving force behind the development of sub-systems.
GTRE and LRDE would have never put their effort in Turbofans and X band MMRs (now AESA) had there not been any Tejas.
Mk1A is a low-risk program not Mk2.
Scaling up an airframe marginally does not change the aerodynamics radically.
MK-2 draws substantially from Tejas MK-1 in absolute terms as well as in comparison to AMCA. So it is not a high-risk program.
MK-1A is not even a low-risk program it is Upgrade with minor tweaks in the airframe.
No you don't. Let's be clear on some things. IAF wanted light fighters to replace Mig-21 hence the "light" in LCA. Mk1A is a light fighter, Mk2 is not.
Exactly MK-2 is not a light fighter, just like Mirage 2000 is also not a light fighter. So no point in buying an MRCA from outside just for the sake of having a Medium weight class fighter. But if such a deal helps in getting substantial help in developing AMCA then why not.
If concluded Rafale deal(MRCA 2) will bring some help for AMCA as well as supplementing MKIs while MK-2 will make for numbers as well as bringing capability on par with Mirage 2000 UPG.
Now that MMRCA has been reincarnated, why would you need another medium fighter?
We need Rafale as MRCA for getting some technologies which are expected to help in the development of AMCA. We need MK-2 to help existing indigenous technology evolve to the standards closer to that of next-generation technology.
Another bad example. Both PLAAF and PAF were flying Mig-19 based Q-5 well into the 2010s, I never found anyone saying that India should continue to use Su-7 because neighbours were doing so.
Both PLA and PA are still using modernized Type-55s. Never heard the same argument for T-55s in Indian service.
If we had not considered the fact that part of enemy's force structure are made of upgraded versions of old era MBTs then IA would have straight gone for replacing its T-72s with T-90 MS, not upgrading it into CIA.
Similarly, if PAF and PLAAF had not been using its 4th gen fighters but only using 5th gen then IAF would not have asked for a 4.5 gen MRCA and would have straightly gone for either SU-57 or F-35 if not both.
Cost plays a major factor in building up an arsenal and fighting a war. Everyone looks for cost-effective solutions this where the evolution of existing products makes sense commercially.
PAF might as well use JF-17s in the 22nd century, should we follow the suit too?
If PAF disbands its military we won't need any military infrastructure on our western borders, nor we need to worry about a two-front war.
Cost of building military capabilities has always been and will always be justified in proportion to threat perception.