I wouldn't say that the ratings have been lower but more so it shows the overall percentage which can make it seem lower than it would without. So for example if someone's most voted score is a 7 but then the the rest of their scores are mainly average, it will seem like they scored pretty good but then the overall score says otherwise due to all the average scores rated.
Yes, you're right about that, it's just a simple mean average. We're gonna add smart average soon (for example if someone consistently rates everyone below average, their vote will be adjusted a little higher and vice versa), we'll also fix the people attacking each other by voting just 1 on their pictures undeservedly. Hopefully it'll roll out in a week or two, stay tuned!