Imo, there can't be much we could have learned from, because simply integrating foreign parts without any co-development in it, won't make us better. Also cost can be reduced by numbers of units beeing made, but 124 (especially in terms of tanks) is a poor number and I blame IA for it!
Be in at Arjun, or LCA, it would have been wise to induct numbers first and upgrade/improve them later, instead of insisting on the MK 2 version of both developments from the start.
My point is, how can we get real experience with the tank, or improve it if only such a small number is operational? Imo, only during operational service, you will find out weakpoints and can improve, or fix them with the next upgrade. But complaining about problems from the start and delaying the whole development and production to get the MK2 version, won't help the forces, nor our industry!
I am not blaming the IA alone, our industry tend to delays and also overestimate their capabilities as we saw in LCA development too, but in other countries it's not going like this.
The German Leopard 2 tank is one of the best tanks in the world, but even they evolved the tank through the years and didn't wait for the improved version.
First Leopard 2 tank:
Actual Leopard 2A6:
And the next upgrade is already under development, Leopard 2A7:
The first order of Leopard 2 tanks was for 380 tanks, the second of improved 2A1 versions was even 750 tanks!
The Saab Gripen was developed nearly at the same time like LCA, of course they didn't have problems with a financial crisis and sanctions, but they was so smart to develop only those parts alone, that they could develop alone and went with JVs for the rest. We instead wanted to do everything on our own and now, when many things went wrong we search for partners to help us. EADS for weight reduction, Elta for MMR, Snecma for Kaveri engine and we still search for partners to make LCA carrier capable and for an AESA development.
The Gripen in the meantime developed from an interceptor in the A/B versions, over a 4. gen multi role fighter in C/D, to the 4.5 gen Gripen NG version now.
So if we had gone with Israel for a radar co-development (MMR and AESA later) and with France, or Russia for engine (both reliable partners for us) from the start, couldn't we had LCA MK1 years ago?
And why doesn't IAF start inducting LCA MK1 before? It wasn't underpowered at all:
LCA MK1 - around 6,4t at that time and 85kN with GE 404 - 20IN
Gripen C/D - around 6,8t and 80kN with early version of GE 404
JF 17 B1 - around 6,4t and 83kN with RD 93
Maybe Arjun MK1 lacks behind in some fields of IA expectations and maybe the T90s are better in some areas and more cost-effective, but we still had gone with Arjun in higher numbers to have a common base to improve from.
Same for LCA, maybe it was not as good as expected from IAF at the start and maybe it was only useful as an interceptor, but we could have replaced some Mig 21 yet and could improve it later to MK2 standard too.
Both was possible, both would have been better way to go, but now both is way too delayed and everybody is already thinking about NG projects like MCA, or futuristic tanks, but you can't move on before these developments are done and they are inducted in numbers!