My DW and I are soon-to-be first-time cruisers (like, in a couple of weeks.) So we don't really have a baseline for how things were. That said, I'll relay a conversation I had with my DW a few weeks back:

...and we need to plan for tips...

Tips? You have to tip on a cruise?

Yeah, it's explained somewhere on the
DCL website...
It's one of those things where if you're not aware you're supposed to tip, you're less likely to tip, and far less likely to tip appropriately (or, at the very least, you're not going to be resentful of the fact that you get hit with this unexpected expense at the end of your voyage.) Now, because I've been reading the boards and the fine print, I had been building tips into the overall cost. To a newbie, or to someone who deals with tips rather infrequently, it's just not something you think about.
My inclination is to think that the pilot program on the Magic was successful enough that they simply decided to roll it out across the fleet. I don't think of it so much as an effort to cut costs/increase profits as it is a more streamlined mechanism to reduce unpleasant or unexpected surprises at the end of the cruise. Most people here do expect to tip, but that information isn't always obvious or evident to a newbie.