That really would be troubling. The iconic Broadland scene to me is an old wooden cruiser in front of (insert any of a number of low bridges here), not a BA ranger in his fancy launch in front of another refurbished boathouse.
I've noticed trends in speeding cruisers over a number of years, and it's funny to note that certain hire yards seem to be worse than others. Whether that's just because they perhaps have more boats than others is a matter for consideration though. And it certainly isn't a problem confined just to hire boats.
It always strikes me as a little ironic; we head to the Broads to slow down and relax, yet there are some people who seem to like going everywhere at full throttle in a cloud of smoke, or trying to get a tired old Bounty up on the plane!