If you want to use Power Surge (which I don't, but I had it pre-IOs) you can cap those, also. With a Brute, who has much lower base numbers. Back then it was tricky to time it, but you could also hit Power Sink as it crashed, refill your endurance, use Aid Self (because of the PBAoE hold that was part of the crash) or greens, and keep going without detoggling. Nowadays you could use Energize instead of Aid Self, which would also help with the -recovery part of the crash.
As mentioned earlier, the issue is you're still getting hit by debuffs without defense, and you have no DDR to protect what you get from set bonuses. That said, my Rad/Elec Brute is pretty hard to kill even without softcapped defense (positional defenses range from 32-36%) unless you're throwing a lot of toxic damage (10-20% resistance with Reactive Defense proc IO).
Surprised I haven't seen more Dark Armor love, though; build it right and it's unkillable, and the Theft of Essence proc makes Dark Regeneration a live-target Stygian Circle to cure endurance issues.