Nevermind my previous post, now I understand the setting.
It doesn't turn off conversion of date strings to javascript dates, it turns off the conversion of all date and time columns, including timestamps resulting in a loss of timezone information from the DB, and preventing any further conversion of times from that point on.
It would be nice if this feature just turned off the non-TZ'd native columns like DATE and DATETIME, while leaving TIMESTAMP alone. But, it looks like we're just going to have to consider our use-cases around due dates and such and look for a different way to solve this.