Voting shares can vote on whether or not the company issues more shares, pays out accumulated profit as dividend, takes on a debt load that may look good in the

Voting shares can vote on whether or not the company issues more shares, pays out accumulated profit as dividend, takes on a debt load that may look good in the short-term but will have a crippling impact on the long-term, etc. An index fund cannot just decide to dump a company's shares because management has decided to drive the company off a cliff for the sake of a quick payoff, so paying a bit extra for voting rights tends to be in their interest.