To you, maybe, because you don't know the real reason for the acquisition nor their next move. But i can tell you this, by Sony being in the position they are in financially, there is a very good reason they would go after a direct competitor's idea to be added to one at which they've already acquired, and it may or may not be game related.
And you're right, cloud gaming isn't new. However, there are many different ways it can be manipulated across the cloud. Hypothetically speaking, you are playing a game that is not online, even though the console is connected online, and a window pops up in the corner of the screen that is controlled through the cloud. What's on that window is at question, but its the IDEA that makes it unique.
Moving on.... when Sony aquired Gaikai, they were much cheaper than Onlive at the time, not to mention them having a completely different way of recognising games ran on their servers. This was explained a long while back, btw, and Gaikai's patented way clearly yield better results in quite a few areas. Anyway, instead of going after Onlive when they were expensive at the time, which is what many had suggested in the beginning before we ever knew it was Gaikai, Onlive, instead, ran out if steam and were still acquired and at a much, much cheaper rate obviously. Killing two birds with one stone, as the saying goes