Agree entirely, not sure why creating an atmosphere has to involve being within shouting (and presumably gesturing) distance of away fans. One thing I noticed last time I was in the away end at Anfield was the way Liverpool fans generally, and especially the Kop, basically ignored the away fans yet still seemed to manage to create an atmosphere and support their team. As to the suggestion that the move to 'A Block' against Birmingham significantly improved the atmosphere, I'd suggest that was more to do with City scoring 4 goals and comfortably winning the game!
Having said all that, I have no problem with fans (especially younger fans) wanting to try something new if they think it will improve the atmosphere, but it has to be done the right way which respects the matchday experience and safety of other fans.