That might be changing, but it still could be a problem for women candidates. Preference Voting Builds Coalitions Bullet voting is more likely to have other negative effects. No matter how diverse a city is, its voters will tend to be multi-dimensional and tend to have shared interests with others who in other ways are different from them. With preference voting, coalition building is an obvious result. The result is that candidates will reach beyond their base, voters will look beyond candidates most like them and groups of voters too small to elect someone on their own will find at least some candidates responsive to them.
Cumulative voting has no such incentives.
It was an obvious choice, and both black candidates and white candidates knew it would likely happen. Such outreach would simply be smart campaigning. With preference voting, candidates will still need to differentiate themselves from the other candidate to gain support, but they cannot be too negative if they want to gain the second preferences of these voters. Preference voting was adopted by referendum in two dozen U.S. cities earlier this century. Now we can computerize the count, and I believe there is more tolerance of diversity.