Keane is nowhere near the top 3. Cantona, Giggs, CR7, Rooney, Scholes, Van Nistelroy - they were all superior to Keane. And these are modern players, you've also got the absolute legend which is George Best.
The World Cup is also a huge deal now, it's the most important trophy in football. And it's not exactly nostalgia, when we compare players from different eras, most of us compare them when they were at their peak, we don't compare how their careers panned out. I agree with you that ZZ is vastly overrated, but the same can't be said about R9. He was just phenomenal at his peak, the best number 9 in history.
And Ronaldinho being better than Messi is not ludicrous, in my view he had a higher peak. Messi can only dream of the things Ronaldinho did with a ball.