So what's the point then?
They get something* for basically nothing. The $10 million in cap space that Perkins eats up costs nothing and might not even cost a roster spot if it comes to that. The downside? Something magical might happen with $30 million in cap space than just $20 million for a team that won't get a superstar in free agency? Iron-clad.
*If nothing else, 1st round picks almost always go for $3 million a piece in actual money and you can sell them. Teams are starting to wise up that picks have value and you shouldn't just piss them away because you can get rotational or better players for extremely cheap and building through outspending everyone else is harder to justify with the new CBA. Picks are the closest thing to liquid capital on the market (besides actual money, I guess).