Whether this tradeoff is the right call is up for debate. As someone who uses iWork a decent amount, it's frustrating that the first update major new release in over 4 years is a regression in functionality.
( Source: Rarebit Studio | Whither iWork? )
I'm not a hard-core user of iWork (although, I do prefer Keynote for my presentations and some diagramming / animation activities) but I'm guessing this is a terrific long-term solution.
Short-term, if you're using any of the more advanced features of iWork, it sucks. (Just like if you're a podcaster and you updated to GarageBand 10 - yikes!) Still, in the longer run, being able to edit / work on any iWork document on any device seems to be a big trade-off.
For me, the importance of accessing my data and applications is still the most important aspect of making things just work.