It dealt pretty well with its subject matter — namely, why, when and how to push your comfort zone in RPGs. Why? To learn about things and lives you’ve never experienced; to become a temporary expert in 17th century piracy or rocket science; to get a sense of what it’s like to be someone very different from you.
They also addressed, very adeptly, that it’s not necessary to push your limits. It’s okay to always play the same kinds of characters, if that’s fun for you and your group. As they said, “roleplaying outside your comfort zone is not obligatory”.
And it’s equally important to get things right when you do play someone very different from yourself. Avoid essentializing. If you’re cross-playing, or playing someone of a different ethnicity, or whatever else, make sure you do your research and make the character well-rounded, not a stereotype. Make sure that their gender, ethnicity, etc. are part of a well-woven tapestry.
One interesting concept that Sherry mentioned was “you play what we say”. In it, everyone else in the group decides each person’s character. If the other players charge you with playing a character very different from your usual type, it could be quite an eye-opening roleplaying experience. This seems like it would only work well with a group where there’s a lot of trust, however.