Why would anyone EVER give a crap about Bubastis?
It's a silly looking giant cat named after a cat god. It's not exactly there because the author wanted you to care deeply about her so much because she was Adrian's genetic breakthrough. She's a plot device and a key "element" to Ozymandias's character, with his reverence for history, Egyptian stuff, etc.
Adrian cares about Bubastis, yes, but probably because she's two things: Unique, and his PET. It's a man and his dog...or in this case, a man and his giant genetally engineered lynx.
You're not really supposed to care about Bubastis beyond that. You're supposed to care that Adrian cares about Bubastis on some level, but that he sacrifices her when he has to. To recognize it as a sacrifice on his part.