They might have been needed back then when China didn't have them. Now that squadron numbers are at half strength it is time to get serious about rebuilding the IAF, not wasteful spending on something that will never get used. If it does the PLAAF and PAF will have been training against the Chinese version for years.
People need to understand how important it is to not have equipment operated by your enemies.
S-400 is a stand alone deterrence system. It's capabilities far exceed anything which is available rn. IAF totally junked patriot thaad we don't need that we have home grown anti icbm system. IAF chief said s-400 is biggest boost which IAF can get with luxury of s-400 and MR-sam regional balances will change in favor of india. Indian navy used tons of equipment which chinese and india shared such as killo class subs su-30 etc tanks.
We cannot afford 75+ squadrons which paf +Chinese airforce will have. Only way forward should be the having a capable squadrons strength plus even better air defence system.
Pakistan can train against rafales to they does that make rafale useless? They train against su-30 does that makes that jet useless certainly not. We also train against F-16.
S-400 is the cheapest air defence system when you see how much area it covers. S-400 can literally make PAF useless.
Our ssb program is created with the help of Russians. Because there is still a common interest + trust. Technically they can share our sub acoustic signatures and all but that doesn't happen. Who knows indian s-400 have a different electronic warfare system. Certainly it's a classified system.
And Chinese doesn't have 400km range missile.
Every system after some years become a lesser capable system. USAF is training against s-300 for years but i don't think reputation of that system is reduced. In fact india going for s-400 shows how capable that system is.
Area denial weapons are better than air superiority weapons in some cases such as in case of subs india used to buy more subs in 90s because we had threat from bigger navy's. In iran s-300 system is a big headache for other forces(you can say Israel fooled them but why they don't destroy that system? Just like they destroyed pantsir (which india rejected tho) . Now again with the growth of Chinese navy IN is getting confused to start building subs fast as we need subs for area denial we have large numbers of ships but very few subs. Chinese build tons of ssk for area denial only now they are building surface ships for superiority. Rafale can provide superiority s-400 can provide area denial.
