The two best pitchers I ever saw were Sandy Koufax and Bruce Sutter. Other great pitchers have had longer careers. But in their primes, they absolutely ruled.
But consider this: Koufax did not throw 200 innings in a season until he was 25; not coincidentally, that was also the first year he ever got his walks/9 under 5!
And then it was 'ride the horse'--his innings totals from that point forward were 255, 184, 311, 223, 335 and 322. Do you think they might have ridden him a little hard? More Sandy Koufax would have been a gift not just to baseball, but to all sports. (ERA+ his last season, when his arm was already shredded, was 190.) He was a guy who could have used a modern bullpen.
A decade later closers had become well established, and no one was more dominant than Bruce Sutter. It's a mistake to say he 'invented' the splitter. After all, people have been doing funny things with baseballs since the 1800's. But he certainly reinvented it. In 1977, he seemed unfair--like Wilt in the key. How does an ERA+ of 328 strike you? Along with Fingers and Mike Marshall, he convinced all of baseball that a dominant closer was indispensible. Before that, a closer was just the best guy on a staff who couldn't handle starting.
So I say bullpens are good...especially if they can help extend the lifespans of dominant starters. And as long as they speed up the transitions, I don't care how many changes there are. I always say that if you're in a hurry, why in the world would you choose to watch a baseball game? :)