A chassis that is wanting of power is not the end of the world folks. I've got a Civic Si, most of my peers spend great sums of money into giving the thing more power, beyond what the car can reasonably handle. The BRZ should comfortably grow into power increases, and because it is so light, those increase won't have to be particularly great to start having effects.
Would substantially more power from the factory be nice, sure, but the BRZ would likely end priced above the other cars in this article. Let's face it, that is not Subaru's market. Subaru wants people to draw comparisons with the Cayman not compete against it in the market.
Add to the fact that since this is the latest inexpensive RWD tuner car marketed toward young buyers, many future owners will be migrating from FWD and AWD platforms. Taking it easy on the power for the first year or so isn't terrible.
The car is relatively inexpensive and seems to be shaping up to be a good platform for modification. Given this thing is being sold in near identical form in almost every region across the world, aftermarket support should not only be strong but also diverse.
I'm not worried, it will be my first RWD car and indications are it will grow with me for quite a while, longer than the Civic that's for sure.