I'll say this: If you can dual-wield two 2-handed weapons, then why would you ever use one 2-handed weapon, or 2 one-handers? And if the reason is the negative stats, I'd like to point out that the two-handers also have a lot more positive stats. Excluding the stuff like the pike and straight pike, you'll typically be getting a lot out of the two-handed weapons that could definitely outweigh the negative stats that some have. Even ignoring the fact that you'll definitely have higher damage on the weapons, the stat bonuses are generally too high for it to be reasonable to say that the one-handers would be better for the bonus stats.
And even if it wasn't for two-handers, if it only let you use non-light one-handed weapons as light weapons, things would be... mostly not actually that bad, actually. While I'd say on average non-light one-handed weapons are slightly stronger, the only ones where one feels like a straight upgrade over the other are curved blade>short sword, flametongue>sanctified gladius, mace>club, and Ashelander>sharp sickle. I'd still be cautious about it, but I don't think letting one-handed weapons be used as if they were light weapons would invalidate the light weapons.