They have shown great consistency across the formats in these last 10/11 years without a tournament win so that should be applauded, and maybe a big reason why it feels so disappointing for Indian fans.
I feel India not winning a tournament is down to 5 main factors with details from the top of my head :
1.Tentative batting in big matches :
India seem to forget in the big matches what got them to the semi final or final, often trying to play too safe, happened in 2014 T20 WC final loss to Sri Lanka where they used up way too many dot balls , 2015 & 2019 ODI WC semi final they looked absolutely terrified, Rohit Sharma tried to get rid of this mindset in 2023 ODI WC but in the final we again saw some ultra negative batting I think there was a period where 30 overs no boundary hit.
2.Poor basics
India have struggled with no balls, average fielding,lack of intensity in big matches .
This is unacceptable, in a final your basics have to be at a high standard,
Think of how many lives they give Lendl Simmons in 2016 T20 WC semi final, if they had dismissed him early they win the game.
Bumrah got Fakhar Zaman out early in 2017 Champions Trophy, but overstepped..Zaman scores a hundred and wins them the game.
3.Preparation
Sometimes it feels like Indian Cricket prioritises IPL cricket more than international events, the second WTC when India met Australia was a farce in terms of preparation for example.
Australian cricketers who played in WTC final made sure they put that first instead of T20 commitments.
4.Met the Better Team on the Day
Sometimes you can just come across a team having a great day , Pakistan in 2017 final looked unstoppable with partisan Pakistan crowd supporting them..NZ in 2020 WTC played a very high level and were deserved winners, Australia at home in 2015 very little India could have done, Australia in 2023 final had a great game plan
5.Selection Failures
Sometimes Indian players have played on for far too long and just use tournaments as a swansong to retire, some players constantly show they don't perform in big matches but still get picked, also India has failed to produce enough seaming all rounders in last decade, only Hardik Pandya who has had injury issues, and lack of competition.