When your team's template for T20 or ODIs is the best example of the definition of insanity, there is very little to feel good as a supporter/fan of that team.
It would be one thing had the team tried to go down the aggressive route as batsmen that was promised and then lost this badly. But the cycle alwyas repeats. We are outclassed in WC KO games, we go back and promise to play a different brand of cricket, try certain players, dump certain players, but just before the WC we panic and either bring back those discarded players or go back to that method of cricket.
There is no way in hell Shami, Bhuvi, Chahal or Kuldeep are good enough bowlers in LO formats to defend picking them over bowlers who can actually bat and/or field, and therefore at least allow our batting to take more chances up top. And with the batting, Rahul is the very definition of a mental midget, and that is being harsh on midgets. T20 teams and even ODI teams need allround options. Unless you have a patently powerful bowling line up like Pak or Aus (and they often go the journey too), it is always safer to bet on #batdeep these days in LO cricket.
Look for enough left handers and enough varieties of bowlers so that you can be prepared for all sorts of match-ups and conditions, give up on uber specialists - and by this, I not only mean batsmen who cant bowl or bowlers who cant bat, but also include players like DK who cant bat when there is more than 20 balls left or Harshal Patel or Kuldeep who cant bowl in the Powerplay etc. - and look for players who have specific skillsets than players who can play specific situations.
Going forward, our investment should start with experimenting with Pant as a LO opener or just dropping him for good from all LO formats for India. Rohit should not be selected for T20s going forward and if we think Pandya is the captaincy material we need, then we should go all in on him now. I would suggest looking at below combination to start with, for our T20 future -
Pant (wk) (vc) (backup- Ishan Kishan)
Gill (backup - Ruturaj Gaekwad)
Virat (backup - Shreyas Iyer)
SKY (backup - no idea, we have no one this good. Maybe Sarfraz Khan)
Tilak Verma (backup - no idea again, need left-handed MO options. For now, Abhishek Sharma??)
Hardik (c) - (backup - Dube?? 3D?? Ideally dont have one but maybe invest in Raj Bawa? Hangergekar?)
Washington Sundar - (backup - Krunal Pandya??)
Deepak Chahar - (backup - Yash Dhayal???)
Shardul Thakur - (backup - Harshal Patel??)
Ravi Bishnoi - (backup - Rahul Chahar??)
Jasprit Bumrah - (backup - Arshdeep Singh)
If we cant see the light after this loss, we never will. T20 is a game of high variance and it brings teams closer together than any other format even if there is a gulf in their actual pure cricketing skills, but even given all that, the last T20 WC was very much more of a lottery with the toss and the conditions than this one and we were simply outclassed by a far better T20 outfit, not just on the day, but I guess overall on balance across all conditions.