It's not hell bent on more speed. Like Jim said, the boat will perform better if you have the right amount of HP behind it. You can plane faster, or if you see a wave coming and need to jump it vs spike it, the HP will allow you too. Or say you are out on the lake and see a thunderstorm coming and don't really want to wait it out on some shore, you can gun it home. OR for the tourney angler....
It's 6:00 am and you are boat # 134 out of launch making a 70+ mile run to the hot spot that will win the tourney but 2 other boats know about it and left before you. However, you can run a good 8 mph faster than they can and so beat them there.....or by having that much speed, you gain an extra 15 minutes of fishing time in the day. Can be the difference between winning and losing.