They took good strong engines and made them dumb and changed the ratings and then on paper it looks worse. In reality up until 74 the early 70s cars were mostly every bit as fast as the cas before them within reason. That's not to say some ratings weren't fudged or sandbagged. It goes both ways. Some engines made more than advertised, others not as much. Hell, there is known examples of the SAME ENGINE in the SAME CAR having more power the the other back in the day.
This is not a muscle car. If you need the extra power, go throw a couple hundred dollar bills at it and watch that displacement come to life. This car is a barge. Your modern 175hp 4 banger is not going to move a yacht of this size. Yes, they built 4 pots back then and yes they got great economy but the lack of power compared to modern day (a typical 2.5L 4 cylinder mdade 85hp average) is why you see such big engines in these cars. Buick 455s were known to be power houses. This engine in it's best year made 510lb-ft of torque. Do you guys have any idea how much that actually is? You simply do not know torque until you get behind a big block...
Sure, modern diesels might school them in peak torque output, and modern day smallblock V8s definitely deliver absurd amounts of power, but the delivery of said power and at least in muscle cars, the lack of refinement (not so much in this car, as this car was pure luxury) was what made them appealing and so fun to drive. If you can't appreciate that for what that is, then I'm sorry you're missing out.
Believe it or not, more automatics back then were used than manuals, much like today. Society was just as lazy. Tech wasn't what it was today. Finding a good solid manual back in the day behind a massive V8 such as this was rare. They made them, sure, but unless you beefed them up they didn't last like the automatics would. In fact, in the 80s you couldn't even get manuals in some cars because they weren't strong enough to take all the torque the anemic engines you guys like to laugh at were putting out. A 7.5L is a 7.5L. You want to laugh at the stock rating? Go ahead. Laugh. Just remember that those days emissions and technoloy wasn't what it is now. They didn't have 45 years of trial and error to make things work. They took existing engines and made them work in whatever way they could because developing new ones to rapidly changing regulations was nearly impossible and developmental costs were too high. Oh you forgot about that? Who's the fool now...
Like a I said, a 455 is a 455. You can make absurd power out of one of these babies. More than you will ever, ever need. Not everyone wants to mod them and that's fine, but don't knock it because the potential is absolutely there. It's up to you to unleash that potential. If you'd rather not, enjoy the car as it is and quit you're bitching, or grow a pair and do something about it.
/endrant