I'm not sure what kind of brutes you've been playing with but they aren't a good rep of what brutes can do. Brutes are the preferred tanks in most content. Stone tank is an entirely different problem all on its own that even these changes won't fix. Tanks also don't hold aggro any better than brutes can, taunt pretty much makes sure of that. Kheldians have a lower res cap than brutes/tanks so unless you're min/max'd to have perma light form you'll be worse off than a brute and do far less damage. The main point of this change is to set tanks apart from brutes more than just their HP and a little extra resistance. City of Heroes is balanced around SO and in the SO based content, brutes and tanks are interchangeable when it comes to tanking ability and it gets worse when you include IO sets. This was never a problem until you could have both on either side. This change would only add utility to the tank to make it feel like "The main tank" as opposed to a tank.
Also, soft cap def is soft cap def. You can't be better at only getting hit 5% of the time than another tank :P and in team play and end game content, neither of them die at all for the most part. So dying less than the other guy doesn't die is pointless. This is a utility change to make tanks have more tanking utility than their brute friend while still keeping brutes perfectly capable of tanking.
Lowering the brute to the tank level is not the right decision. Fury does a solid job in setting it apart from the other classes and makes brutes really enjoyable and unique to play. Tanks just need some change to have the same feeling. Something that will set them apart from everything else and i feel this change would do that and make tanks untouchable when it comes to tanking utility as opposed to now where tanks preform the same as their villain counterpart but do less damage.