Boom trading is the "new double TC"

Yes, but that doesnt mean there is no aggression.
French strength doesnt come only from faster vill but also from their aggression with knights, Rus is kinda similar as well.

In all aoe games so far, not sure what the state of aoe3 is right now, but when i used to play aoe3, in higher levels rushing was always weaker because top players were much more skilled at deffending and they are much better at not loosing villagers, so they leaned into greadier and greadier playstyles and the same applies to aoe4. Only way to change that is by making some drastic change like moving tc to age3 or something like that.

Also I may be wrong but even in aoe2 from the little i watched it and played for a while, the meta was to fast castle so players could get their 2nd and 3rd TC.