Richard Baldwin at Vox wrote a column that makes a practical case for why voting weights matter. He produces a chart - you gotta love charts - showing the relationship between EU15 countries' EU budget share per population share and their Council vote share per population share. There's a correlation, as you would expect.
The chart also shows that the current voting rules are relatively kind to Finland, with only Ireland and Luxembourg in the EU15 having more voting power per person. Finland hasn't managed to turn that vote share into budget share particularly effectively, though. Baldwin has a theory on it:
[T]he EU members that joined in 1994 - Austria, Finland and Sweden - are far below the average relationship between power and spending. In other words, given their level of votes per person, the relationship between power and spending that one sees in the older members (the EU12) suggests that they should be getting more EU spending per person. Perhaps this reflects the fact that these newcomers have not yet learned how to work EU politics in their favour, or maybe they have not had time to do enough 'back scratching'.