I don't play a monk, but from my understanding of the situation, the AGI factor was scaled wrong from the beginning allowing monks and scouts to tank mobs if very high level by pumping their AGI very high. The purpose of AGI is to help in avoidance. To counter this "fix" you should still concentrate on AGI for the avoidance factor, but go for raw AC items if you want to be an effective tank.
AGI was a bonus to Scouts and Monks as they could only wear medium armor. Up until now, it didn't matter what armor they wore as long as they pumped their AGI to an insane value. Monks did not get nerfed, nor did scouts, instead they fixed an exploit in combat calculations which allowed for ridiculous tanking ability.
Something that must be understood is that while monks/bruisers are part of the Fighter class, they are the lesser of the 6 types in terms of damage absorbing ability. However, they are the highest in damage output. Just as base class roles are differentiated, so are the sub class roles.
Fighters are divided into basically 3 main categories: Warrior, Knight, and Brawler. Each one is a degree of seperation from the next. Warriors are the meat of a group, they take the damage that the other two cannot. With that in mind, they also dish out the least about of damage of the three class divisions.
Knights, are a good balance of damage input and damage output. We cannot take near the hits a warrior can, and we cannot output as much damage as a brawler.
Brawlers, while able to do faster, more disrupting damage, cannot take the beating that a plate wearing fighter can.
To me this is the way it should be. We are all, as fighters, capable of tanking for a group geared to our levels. Within this realm, each division of the base class is more capable in one area than the other, or in the case of crusaders, more well-rounded and across-the-board even in all departments.
For example, brawlers, to my knowledge get faster attacks, and more stunning, knockdown attacks than a warrior, allowing them to prevent attacks from even getting off at the rate they would to a warrior. Less attacks getting off, means less hits incoming.
Monks WILL without doubt take more damage from single hits than a warrior or cruisader, however it is not the damage you should be concerned with, it is the amount of times you get hit.
Use your ailities and self buffs (i.e. cruisaders: Knights Stance - SK: Zarn's Aura and the lvl 30 upgrade). These buffs enhance your class-types main defensive/offensive aspects.
As I have mentioned, I do not play a brawler type, and I do not have a want or need to, I love playing a ShadowKnight. So my best advice is to experiment with your armor/weapons, and abilities.
Might want to get together with a few monks and experiment with different things. Try buffing yourself using different self abilities/spells, and see how that works out for you.