Vehemently disagree. Such views are based on emotion.
Let me modify/clarify my position a bit. Not everything can be harder in a world cup match. That's not mathematically possible. You cannot have poorer overall batting averages, poorer bowling averages, poorer strike rates and poorer economy rates all at once just because it is a big stage. Someone will play big knocks, someone will take wickets, someone will hit boundaries, someone will bowl economically.
If indeed batting is harder on big stage than consequently bowling is easier and hence bowling performance in a JAMODI must be valued more than in big games. If chasing a total is harder on big stage than consequently defending a score is easier and hence good performance while defending a total in a JAMODI must be valued more than in big games.
There is pressure, yes. But pressure is on both teams and it cancels out. Or if pressure does make one discipline harder it must by corollary make the something else easier.
I'm sorry but this is spoken like someone who hasn't competed in sport in a pressure situation
Everything is different when you play a game with stakes on the line. The difference being is everyone has a lot more nerves, and the fear of failure is far greater. To be able to control one's emotions and execute your skills properly in a pressure situation is an incredibly hard thing to do. Players who put in big performances in these circumstances are usually the ones who have overcome those mental hurdles.
In a regular cricket game you're just seeing the skill vs skill clash. Which players can adapt and perform in those specific conditions, which players find their rhythm right away, who has the luck going in their favour. These factors determine who puts in the big performances. In World Cup (and other important games) these tend to get overridden by who can keep calm and deliver. Think of Grant Elliot for NZ vs SA.
And sure there are pressure moments in a regular game, and even regular JAMODIs can get pretty heated. But in World Cups and other big tournaments, every game and every moment matters. You constantly have that added dimension to it. It's why the heroes in these games can often be guys who don't normally churn out performances in a mechanical fashion in JAMODIs.
Not only that - but no one is going through the motions in a World Cup game. In JAMODIs you see players play within themselves to preserve their bodies for important cricket. You see players who have mentally checked out and are just there to collect a paycheque. In World Cup games, everyone is zoned in, everyone is hungry, and everyone is leaving it all on the field. It's a different level of intensity. You're also playing against the best possible XI - in JAMODIs, teams play fringe players and try out different combinations and strategies.
You can't compare the two. This isn't a statistical exercise. Emotion matters in sport. That's why we watch it.