Agreed. There is no real point to it other than the 'wow' factor, which is not so much these days. That being said, I prefer the push button start.
As for locking the keys in the car, I think you can do it if you use the button on the door as you get out. On my car, I can't lock the doors using another fob if there is a fob in the car. Kind of backwards really, because if you have another fob on you, there is no danger of getting locked out.
This is similar to what I did. I bought a key from the dealer and keep it in my wallet. Problem solved. For a lady, maybe keep the spare in your purse?
Worse case scenario, if she absolutely keeps making the mistake of locking the keys in the car, maybe this is the answer, put it right by the push button and paint it to blend in.