It's sad because basically the series was going so well until Insomniac came up with a new idea (NOT RUNNING OUT OF IDEAS, NEW IDEA) that they could add a bit of co-op to the series, but they were wrong. People didn't like the co-op, people hated the camera and style that was required to make the co-op work.
So now people want this 'final game' to END the series, simply because they thing Insomniac are running out of ideas. With everyone saying that they could very well stop with Ratchet and Clank. 2013 could be the last year, but I don't want to see that happen. Insomniac are very creative, they've kept the Ratchet series alive for 10 years, each game better than the last, until they tried something different.
Obviously FFA is Insomniac's chance to semi-revive the series, it works well as a mini-game because Insomniac introduced this tower defense thing while putting the camera back and keeping the co-op feature, indfact in FFA they had the co-op feature done just as people wanted it to be back when they wanted it. The only problem was the tower defense parts. However (I might be wrong but) people liked FFA more than A4O. And it was made using A4O's style and stuff, just like QFB so if it didn't do too well it wouldn't hurt the company as much, as they didn't have to re-do as much as if it were a full title.
I think that FFA looks a lot like UYA online, maybe that's what they wanted, to bring people back to the ever so popular UYA online for a small price?
Insomniac are just trying crazy new ideas, they aren't running out. The only thing they are running out of is support. Until people see this Ratchet & Clank might not have much of a future. I really like R&C, and want to see another 10 years of awesome games! Insomniac can do it.