AT&T has added a new postpaid data plan option for "tablet" users—which for now means iPad and Galaxy Tab users—that lets you add the charges to your monthly wireless bill. Pricing is the same as the pre-paid options, but at least users that opt for the 2GB per month plan get a much more sensible $10 per gigabyte overage charge.

The current prepaid plans for iPad and Galaxy Tab users, which AT&T will presumably offer for other tablet devices in the future, include $14.99 for 250MB per month or $25 for 2GB per month. If you run over your data allotment within a one-month period, you are charged another $15 or $25 respectively for another 250MB or 2GB allotment—again limited to the current month. Those charges get automatically deducted from your credit card every month unless you cancel.

The new postpaid plan offers the same $15/250MB and $25/2GB options, only the charges will be added to your current AT&T monthly bill instead of being charged directly to your credit card. Users on the lower 250MB-per-month tier will still be charged an extra $15 for another 250MB. However, users on the 2GB per month plan that go over their allotment will be given an additional 1GB for the month for just $10—similar to the overage charges for AT&T's smartphone data plans.

Like the prepaid plans, the new postpaid option doesn't require a contract or term limit. And if you opt for the 2GB plan, AT&T is offering a free month for a limited time. You aren't even required to be a current AT&T subscriber—AT&T spokesperson Seth Bloom confirmed to Ars that if you only have a tablet device, you can sign up for an account to opt in to the new billing.

The new postpaid option does offer the extra convenience of adding tablet data charges to your monthly bill. But aside from the $10 data overage charges that oddly seem to reward the heaviest data users most—at odds with the primary justification AT&T gave for switching to tiered pricing—the plans don't offer any better value than prepaid pricing. Lower-tier users pay $60/GB on the chance they never go over their 250MB limit, while higher-tier users pay $12.50/GB—or less the more data they use.

"Our new billing options give customers the flexibility to choose how they prefer to be billed,” David Christopher, chief marketing officer for AT&T Mobility, said in a statement. However, we believe users would prefer the flexibility to not be billed separately for each device. Why bother getting a 3G enabled tablet when one could pay an extra $20 per month for a smartphone's hotspot feature, and share the data connection with an iPad, Android tablet, laptop, and other mobile devices? As more and more users have multiple mobile devices, purchasing a single data allotment to share among them seems to be the only pricing strategy that makes sense to consumers.