If you want to be a bad product manager, treat product development as a democracy. Give everyone an equal vote in all decisions. You are part of a team after all, right? What kind of team would it be if people were excluded from certain decisions? When considering new features for your product, let all of the engineers and marketers and salespeople vote, and start working on the feature with the most votes. Let customers vote, too — you’re building the product for them so they deserve this opportunity.
If you want to be a good product manager, rely on leadership rather than voting to drive product development. Of course, product managers can not and should not be dictators, and there are many things product managers must do to engage and utilize the entire product development team, like selling requirements to development and involving others in creating product plans.
However, product development is not a democracy. There is no voting, and if there was, not everyone would get a vote, and not all votes would be equal. While it may be tempting to structure an open process by which stakeholders have the opportunity to provide input and are given a level playing field, this is really an illusion and a disservice to the product manager. If everyone gets an equal vote, then why have a product manager at all? All you would need is someone to tally the votes.
The product manager role is especially crucial when there is differences of opinion about aspects of the product. The product manager must step in to make decisions and lead the product development team in the right direction, whether it is setting the long-term strategy for the product or resolving an implementation detail.
This is not to say that the product manager has ultimate authority over everything in the product — quite the contrary. In most aspects of product development, while most people should have the opportunity to provide input, ultimately there is a person or group responsible for the decision and execution. You would not let an engineer vote on the name of the product any more than you would let a product manager vote on what database software the product should use.
Product managers are responsible for what the product should do; do not attempt to absolve yourself from that responsibility by pushing decision-making back on to the product development team or a wider group. Good product managers are able to get input from all of the relevant players and use that information as basis for decisions. Not everyone will agree with your decisions all of the time, but if you do your job well, your decisions should be understood and respected.