While Sony already owned Ratchet & Clank and Resistance, neither franchise would flourish without Insomniac Games. So, while they didn't acquire any important franchises, they invested in and strengthened ones they already owned. The reason we haven't seen a Resistance game this gen (what is this "burning skies" you are talking about) is probably that Insomniac were working off for Phil and Mark. We had one rushed Ratchet & Clank game this gen compared to over half a dozen last gen. Thanks to this investment, Insomniac can keep those borderline dormant franchises alive. And hopefully make more new IPs and Spidey.
So, I'd argue that they did sort of gain some important IPs from this acquisition. A dead IP is not valuable.