1. Mundo is a health-tank bruiser. There are 2 types of tanks- Health, and Resistance. Shen is another health tank. So is AD Sion. Leona and Taric are examples of Resistance Tanks, they build AR and MR and win as a tank, because nothing hurts them!
2. DFG is a nice item, and with it's current nerf, it is a lot less viable against a team with more than 1 bruiser, ie Darius going top with a jungle Maokai and a support Jarvan.
Your AP caster will now invariably fail, since any gank made against your team is almost bound to succeed, and late game, the APC is left with 2 targets- the AP carry they've been dueling up until then, and the ADC. Chances are, the enemy AP carry is more fed since their jungler could gank without pause, due to the innate tankiness of Maokai, thereby leaving only the ADC to focus. Good job, you can kill 1 person, then you are worthless!
Now granted, this is just one of many scenarios, but I really don't see how teamwork can help, because if Maokai, or any good initiating jungler, camps mid, you as the AP carry are effectively shut down, leaving all the farm to the enemy.
Honestly, BFT is a great item, but only on APC's that have low cooldown pokes. Heck, if brought to classic, I can see how easily it will be abused. Ezreal for example, would be a humongous menace. His Q would be a diabolical poke, and if he got Madred's as well, GG, he can burn through health like a forest fire through a paper factory.
I for one, would like to see some way to make APC's more viable late game, such as an item that deals a percent of life, or something that can change the damage from magic to physical. Then, if the enemy stacks MR, woops, no AR, now mage is viable again.
Also, Elise does percent damage now.