We have evolved enough as humans and feminists to understand that plastic surgery is a personal decision, and that while there are larger conversations to be had about expectations for women when it comes to aging, ultimately, what someone does with her face or body is none of our business.
Until she becomes a sentient face canvas with what appears to be a butthole attached to the back of her mouth. Then we call her a Doctor Who villain and worship at her fabulous... feet? Skin flaps? No, god, no that sounds way worse.
Lady Cassandra is the last "pure" human before mankind began procreating with other life forms. She has had 708 plastic surgeries and doesn't look a day over just-a-piece-of-skin-with-lipstick-on years old. In possibly Rose Tyler's finest moment, she refers to Cassandra as a "bitchy trampoline." We're here for it. Bouncy castle, indeed.
With no heart (or any other organs for that matter—and oh boy do we have questions), Cassandra still has a bit of a soul. She just wants to feel pretty. And, for the love of god, MOISTURIZE HER.
(Lady Cassandra is also technically the only trans character in Doctor Who's history, but it seemed a tad more "funny one-liner" and less "we are very inclusive," so we'll just leave that be. No points awarded.)