The problem with SCTP isn't that you have to upgrade your server or that you have to upgrade your client, it's that you have to upgrade your cable modem, your firewall, your VPN, etc. Of course, a lot of the routing stuff can treat SCTP just like TCP, but they have to know how to do it. Also, if your system offloads some of the TCP calculations to the NIC, you might need the NIC to have SCTP offload in order to get the same performance.
Google's goal is probably something like making Gmail on Android phones fast. Cell networks are probably the biggest current common case where the latency impedes making full use of the available bandwidth. They're also a case where third-party hardware is doing NAT, and Verizon isn't going to run out and replace their expensive equipment to help Google.
It's ultimately the right solution to the problem, but that doesn't mean that an interim solution isn't needed.