The only aspect of the game that has evolved significantly for the better, is fitness and athleticism.
Sports science has allowed coaches to make players fitter, faster and more agile.
Players are technically no better than they were 20 or 30 years ago imo.
You can talk tactics and formations all day, only one thing works consistently....
Pass and move, pass and move, pass and move. Very simple. Pass it to someone in space, move into space.
The difficulty is getting players to do it well on a consistent basis and thats where quality comes in.
The better the standard of player, the easier it is to man-manage. The theory behind it is simple.
I do understand your point as the game itself can be picked up and played with relative simplicity, but at this level and at a coaching level the game extends to a bit more than simplicity.
Your theory is very simple yes but the application is another matter all together, and if the game wasn't so complex or over analyised the English style would still be the one that was developed as the gentlemans game all those years ago.
Tactics and formations have changed far more than you obviously know, and that same over analysis was the thing that led to the basics of pass and move you herald as being the only thing needed to make the game simple.
The English game was solely developed on dribbling and the odd long ball to the wings from the backs. The Scott's developed the coaching style that lead to the modern way. The Hungrians built on it, the Southern Americans developed the skill game, thats evolved into parts of dribbling we see these days, the English adapted but to a W-M formation, the Hungrians further developed it and so on, tactics, formations and set ups have all had to evolve to the theory of pass and move. And as you say the game has now had to evolve with sports science producing the better athlete.
Pass and move has to over come the challenges of shape and set up, pressing of players, positioning of players and marking. Which makes it more complictated and complex than when first thought of.
And the theory of better standard of player should be easier to man-manage, is simply theory, players still have differing personalities and traits, players still learn different and develop at different ages, some learn quicker than others, others take time and when applying those conditions to a team game, it extends from simple to more complex, which is what Bergen was probably pointing at.