Experience has taught me that differing opinions can be resolved by examination of facts and employment of common sense. Also I've been wrong once. I thought I was wrong but it turned out I was right.
Common sense resolves the issue, but not from the perspective of realism. Even though realism is a fun topic I bring up all the time because it gives room for creativity, all attempts to explain balance with realism are futile. This applies to players' as well as balancers' perspectives. What's realistic and what isn't can and often will be distorted within a video game. Everything can be rationalized with realism in a more or less convincing manner, be it a concept that supports or undermines balance. That's the point I was trying to get across.
Consequently, your common sense explanation takes another view: The leveling system had been changed long ago. However, balancers forgot to adjust STR requirements. Because of this mistake, the highlevel-whoring community got used to equipping almost all items regardless of their builds. Now STR requirements have been adjusted, and the luxury of playing agility-centered and balanced builds without any effective armor restrictions is gone. Sorry there's been an obviously overpowered niche during all this time. And extra sorry for those who relied on it to the extent that their enjoyment was solely constituted by it. But neither of that was ever meant to happen in the first place.
Nobody intended to let the new leveling system affect balance. However, not enough measures had been taken during the introduction of the new leveling system, so it DID affect balance. The current patches are meant to revert to the previous balance. Except that the new leveling system is kept, because reverting to the old leveling system is unfortunately no option.