Obviously this would take time to implement and sure there may be more important things to do. However, this could drive revenue so I wouldn't say it's the most unimportant thing.
I honestly highly doubt that. People can already see what stars there are. And since star prices are confidential, there's no possible way of knowing how much you need to spend to get higher stars. I can guarantee no one will spend more money to try and get one just because they can preview it next to their name.
Call it intuition.