I certainly don't think ODIs between World Cups are meaningless - not at all. In fact there'd be no point at all in a World Cup if you didn't play other ODIs, because no-one would be any good at the game. Either that or it'd just be a-la 1975 and a glorified Test-match with a bit of difference.
But seriously - who takes any long-term pleasure from the result of a ODI series? This is a genuine question - me, I couldn't care less about winning a ODI series, it's all about developing a team to win the World Cup for me. It's no consolation whatsoever to me that we either won the CB Series or beat South Africa in 2003 now. None at all. If we'd been hammered in 2003 and Vikram Solanki and the like had been chucked-out the team sooner, meaning we had a better team this World Cup, I'd have been delighted.
I see the point about winning the Chappell-Hadlee series being nice for Aussies and Kiwis, but... how many Kiwis are going to be celebrating that in the event of an all-Tasman WC final and an Aussie victory? Not many, I'd guess. Maybe I'm wrong.
As to what's the point in Test cricket: to me, every series is a thrill in itself. You're not building for anything, you're not looking towards any event on the horizon, you're just playing the team who you're touring or hosting. Test cricket is a continuous event. ODI cricket is not. It goes in discreet 4-year cycles.
And that's why "prepare for the next Ashes" angers me such a lot.