This has been asked, discussed and answered so many times, that we also had it highlighted in the manual, in a big, bold, blue box...
The problem is not so much doing the animated characters, but it's more like we don't know if FSX can handle it, with the biggest limitation probably being the very limited amount of free VAS (memory) due to the fact that FSX is a 32 bit program and users like to stuff it with too many add-ons at the same time in the same area and/or are not willing to compromise with graphic settings, so we are already in the situation were a complex airplane on a detailed airport is barely fitting in memory without crashing, even without visible passengers, and adding them won't surely improve this.