Here’s what makes them different: Amy is broken, angry, and scared of responsibility. Clara is responsible and often afraid, but typically adventurous and light-hearted. River is sensual, capable, independent, and self-sacrificing. Their lives do not all revolve around the Doctor. Amy’s life is a struggle between home and adventure, and that is SYMBOLIZED in Rory and the Doctor. Clara lives a perfectly normal, happy home life and jaunts off with the Doctor on Wednesdays. River has a whole life outside of the Doctor, with friends and a profession she loves. Her life kind of revolves around the Doctor, but she was programmed to kill him and then she married him, so it makes sense.
I can say that Rose, Martha, and Donna were all sassy, had low self esteem, and didn’t follow orders. How does that sound? You cannot boil complex characters down to their most basic traits and then say they’re all the same. Rose was very flirty. Donna was very fiery. All of their lives revolved around the Doctor. Rose in particular spent years doing nothing but searching for the Doctor.
This is not a Moffat problem. This isn’t a problem at all. This is an issue entirely made up by fans who want something to complain about.
I mean, can you imagine Amy looking after teenage children for a living? (You might have a bit more leeway after Series Six, but I’m still not sure it’d be something she’d ever want to do.) Or Clara being a model? We’ve seen both River and Clara stand over their mother’s grave but it was only Clara crying, River didn’t shed a single tear. Would Amy have ever declared she did something ‘disgracefully’? Would Clara ever call someone ‘stupid face’ as a term of endearment? And so on…
Yes yes yes yes yes thank you