It was always the case - even in 1971, it'll be the case in 2071 as well.
The simple reason is - handicap. The ODI game (In fact Cricket overall) is designed to favor batting - rules are to protect batsmen, to encourage batting heroics, to restrict bowlers & to limit bowling advantages. For example, a batsman can bat for entire 50 overs & score 170*, a bowler is limited to 20% of overs.
This is the reason, why ODI will always be dominated by teams with better bowling attack (we can add fielding as well, which compliments bowling). Most people don't see that, because the scorecard doesn't do justice to bowlers, and very few common fan is actually capable or interested in digging deep to analyze bowling - a bowler can bowl absolute gems, still might end-up 0/50; same equivalence for batting might be 58 (48), which everyone can see & go crazy about. But, common people don't see the skills of bowling to restrict a side for under par score. If I am to find an equivalence of today's opening spell by Amir in a WC Final - probably it's equivalent to Gilchrist's innings of 2007 Final - most people'll forget this spell, by the next time when Amir goes for a bashing.
The best teams in history were always bowling dominant - they had at least solid 40 overs. On top of that, couple of their bowlers who would walk into any team as specialist bowler, could do significant damage with bat as well. That's why, in cricket, particularly ODI cricket - the MVPs are bowling all-rounders, players who make the team on bowling merit (Or capable enough to bowl 10 overs) & can contribute/dominate with bat. In his hay days, in Asia, MoHa was the MVP of ODI team - I being the harshest critic of MoHa would admit that always. And, there is no bigger ODI cricketer than Wasim & Viv - though market size determines experts' lip service these days.
