Conservative marketing. Most turbo cars, petrol and diesel can be mapped up a lot. It's not a Honda thing, it's universal. People like us are very enthusiastic about our cars and the engine performance is very important. Further to that, we often tend to be driving minded, feeling the car, the road, the general dynamics of inertia and acceleration. We understand the road and the car better than the average driver (on the whole).
My dad on the other hand (generic accountant in his early 60s) would be happy with a comfy, smooth ride and couldn't car less if there is untapped potential in his engine. Further still, if his engine was a bit more poky, he'd might even be a little put off. Overall composure is key. Believe or not, we're actually a minority in terms of car buyers when it comes to what we want from our motors.
There's no doubt in my mind that the cars are made well enough to handle the power upgrades, but by keeping them tamed down, you further increase their potential for reliability, keep them as calmer drives, appealing to old people with the disposable income to buy a car new (as opposed to the 2nd hand market) and perhaps keep the power within certain emission/tax band criteria. After all, increase a cars BHP, possibly increases its undesirable gas output which in turn will have negative impacts on its tax band. A major factor in modern car sales marketing, in the UK at least.
My car costs about £280 a year to tax. Some people at work have new 1.8 diesel BMWs that cost about £20 a year!!! It was key in their decision to buy. They could get their cars mapped, but do they care? No...
