In no way an influence on my decision, purely a view/theory but I think there are a number of reasons why the atmosphere seems "lesser" at the new stadium.
I think they fudged up the idea of the wall, they should have mapped it out for fans that want to create a din so they could move over from the old stadium to there (if they wish). They didn't do that and its also a mix of different ticket types which means a different dynamic between fans.
I think the music before hand is far too loud and suck the energy out the fans, I really think its a killer to the atmosphere not a plus
I think the stuff going on in and around the concourses has a distracting impact on the overall atmosphere, I was there one week and the drummer was belting out the same thing for 30 mins, by the time I got into the stand my head was cooked from it, was too much.
That said, I love the new stadium for what its, but its different, where as the old stadium was more like "get in see the game, get it off your chest for 90 mins, leave" the new stadium is the complete opposite.
I think fans have changed not the stadium
I've been in WHL when we were brick and it felt that the fudging stadium was going to fall down from the noise and banging
I've been in the new one when we are winning and the atmosphere is brick
And it's not tourist, or new season ticket holders, like a lot of society, entitlement, years of media pushing a narrative, a view that the team is here to entertain and if they don't we can be as brick/stupid/boo/whatever as much as we want. A view that my club isn't good enough unless I can lord over other fans with "accomplishments", when the fudge did how much you care/support you club become directly related to if we won a trophy last year?
Watched the highlights of Leeds playing this week (and yes, fudge them), but the way the crowd was behind that team is something all top 6 sides have lost (unless blowing away opposition or on great run)