G&K introduced a lot of changes that made it incredibly difficult to take cities without overwhelming amount of ranged support which would quickly dwarf Melee units and tactics. You pointed it out by calling them GDRs, and this change means that if I move 4-5 melee units of appropriate tech and age around a city they will get a small boost so they can actually take a mature city that has appropriate tech walls.
It gives the attacker a small boost, that is even better when the opponent leaves the fields unopposed. It gives the defenders reasons to go meet the opponent outside the city walls. It gives a good bonus to attackers that manage to blitz and surround a city and if the attackers still lose, because cities and ranged units are still going to be really good on defense, they still come out with a little bonus gold and some lasting damage on the opponent.
They fixed a lot of problems, so I fail to see how this is irresponsible jenga playing...
1) Pillaging sucked, which meant UU and UA involving pillaging also were lackluster.
2) Mounted units when they don't have an overwhelming str bonus sucked, despite having more MP.
3) Melee units struggled to take any cities, while ranged units (despite cities being near GDRs) were doing mostly fine.
Maybe 25 is a little too much and it might need to be 20 or 15. I'll have to give my feedback after I've played a few games (probably this weekend) but I find the solution pretty elegant and interesting... Even if ya... It's "new".