Except we're not talking about scrapped together builds. Or are we? That's the problem, what is the balancing point you start and end with, if you start balancing around IOs? And again, using your example, what if it's Brutes that choose damage or recharge as their IO build focus and not defense or resistance?
EDIT: And how would the DEVS (again DEVS, NOT PLAYERS) make that determination of what to balance around? Does that new balancing point become the one true way to IO out your build? What if players then find a new balancing point, or the devs release new IOs that move that goal post? Are we prepared to keep playing wackamole with balance based on what the changing IO meta is?
EDIT2: If this game were still live, and had a full paid dev team, I might be moved on the argument for us to start considering IOs for balance. As it is now, with a volunteer team, NO. There are too many permutations for those builds (including billion inf builds, 250 million builds, and frankenslotted cheap builds) for us to waste precious dev time playing wackamole with that. I'd prefer if the devs focused on things like more content, actually fixing the bugs that were left over from live, etc etc etc).