Firstly, LCA Mk1 is nowhere close to being a 4.5th gen fighter. It is still an early-mid 4th gen fighter. Very few avionics aspects are close to 4.5th gen like the OBOGS and health monitoring systems. Radar, EW suite on Tejas, all of that is something you will find on Jaguar, Mig-29 and Mirage-2000 too. What differentiates a 4th gen and 4.5th gen fighter is AESA technology, apart from some specific avionics and aerodynamics qualities inherent to these aircraft. Whether MK2 comes to that standard we will see.
So if we put ASEA on Jag and Mig-29 will they become 4.5th gen fighter? RSS fly by wire deltas with a high TWR ratios along with clean config RCS of less than 0.5 sq meters enabled by high composite usage ,
is what defines most of the 4.5th fighters of today, (I don't consider JF-17 as 4.5th gen , and neither do PAF which is importing second hand F-16 As in a hurried manner )
Even if tejas mk-1 does not have ASEA it can be upgraded with ASEA in MLU, So it won't be barred 4.5th gen fighter tag for lack of ASEA.
Still tejas mk-1 has all other qualities like low RCS with high composite usage, high TWR , RSS fly by wire compound delta airframe,
No single TYPHOON is equipped with ASEA. SO it is not 4.5 th gen as per the standards explained above? Queer thinking!!!!
Secondly, Tejas, Jaguar, and MKI are our own birds. We can integrate whatever we want on them, we can modify them however we like. The fact that we are changing the engines and adding radar on Jaguar is testament to that fact. We are also unilaterally modifying MKI to fire the Brahmos, we can't do these things on Mig-29 and Mirage-2000. Neither on Rafale.
What ever we do on jAG, WE CAN'T FIT IT WITH A RADAR BIGGER THAN IT'S NOSE CONE.
There are no plans to integrate American weapons on Tejas except for the Paveway that we get from the Israelis. Jaguar will receive American weapons because we signed an exclusive contract with Raytheon to add the Munitions Control Unit that allows a non-American aircraft to carry and use American weapons. So, as long as Tejas does not get this kit, it won't carry American weapons.
As of now, only Israeli weapons are our best bet on Tejas because the Israelis are happy to provide us with the relevant technology. Of course, we pay two or three times more than the Israeli military pays for the same stuff. But who's complaining.
As long as IAF finds those stuff good enough for the money , no one should complain. Any way Tejas has r-73 a russian WVR as well and fitment of Astra is only a few years away. SO there is no need for any other american weapon on tejas.
As of today Tejas is cleared for R-73, Paveway-II and Griffin. In the future it will carry Derby, Python-V, KH-35 and Sudarshan. In a bit far off future, it will carry Astra, Helina and other Indian weapons whenever ready. Crystal Maze is a possibility as well and so is the next gen Israeli LGB being made today. Overall, the weapons config of Jaguar and LCA will be very different. One will be American/Indian and the other Israeli/Russian/Indian.
Tejas cannot be compared to Jaguar for the same reason as why a sedan cannot be compared to a pickup truck. Tejas is designed for an entirely different role that has nothing to do with Jaguar.