eh, I don't really agree with the OP but there are some serious downsides to the tablet.
It's got to be the most expensive controller ever included with a system and that's driving up the cost of the system. Maybe manufacturing costs will drop a little bit but unless Nintendo is going to sell the system a real loss, those expenses are passed on to early adopters as well as people that wait for the system to build a good library. How much of a price-drop can Nintendo afford in 3 years? Probably not as much of one as they could have had they not used the tablet. That screen and the chipset and battery that makes it function are expenses that aren't going to go away.
I have no high hopes for the battery either. If the range for the tablet was 50 feet, and I could use it around the home without any problems, i'd be cool with 3-4 hours of use, but if I have to be within 20 feet of the system, there better be some serious battery life in the tablet (10+ hours per charge). If I'm tethered to the system by wireless range, don't tether me to the charger, too--it really defeats the point of having a wireless controller in the first place.