I like the protection, honestly. We've got enough draft picks this year, so we don't have to take another one unless Dallas winds up in the lotto (of course the top-3 is emergency insurance for them).
And next year, even if Rondo stays, Dirk will be a year older and it doesn't take much to fall off in the West. We don't need the pick now and we take a gamble that it'll pay off next year.
EDIT: The more we learn about the trade, the clearer it is that Danny was going for spreadsheet assets that maximize flexibility above all else. We'll see if it pays off.