Amanda Ripley was fine as a character. She's no deeper or shallow than her mom was after the first movie.
People also have the tendency to insert their selves into every fps character regardless of whether or not the character is male/female or what color race it is.
Vs 3rd person where everybody remembers Joel/Ellie, Nathan Drake, or Lara Croft.
Shepard could be a little different if you changed the character to reflect you at the beginning of the game, or whether or not you left him/her standard. And the fact they had three games to develop the character in.
I really don't mind they are taking Ripley jr and running with her because she was the only face to latch onto to sell the EU media outside of Zulu.
They did the same thing with Ripley, Newt, and Hicks in the 80's.
You don't NEED those characters to sell everything, in theory you should be able to sell your product without linking back to other products in the series.............but it is a whole lot easier if you do.
They tried their own original characters in that mediocre aliens/predators/prometheus crossover and everybody really enjoyed that......