Pre IO era is irrelevant, that's not the game anymore. The game has changed, you can't balance around obsolete content, you need to balance around current content. The current content is IO's and set bonuses. Maybe it made everything too powerful, I don't disagree but it gave build customisation a lot more depth, when it used to just be slot two accuracy, damage, end reducs/recharge on a power.
In current high end content, having your defence dropped by half every minute is a big deal. It's stupid. What other power in a set screws you over so much so frequently to the point rage does?