I understand your frustrations, but behind the scenes we have not dropped the ball or given up on SLI. The rule of thumb is this: if there isn't SLI support, there almost certainly isn't multi-GPU support from the other firm either. Why? Because the game engine isn't compatible. If this is the case we'll work as closely with a developer as we can to remedy the problem(s).
Let's address the list from OP:
Ryse - No SLi Support // SLI now supported in concert with new game update
Middle-earth: Shadow of Mordor - No SLi Support // Engine incompatibility
NBA2k15 - No SLi Support // Engine incompatibility
Wolfenstein: The New Order - No SLi Support // Engine incompatibility
Titanfall - No SLi Support // SLI supported for some time
Elder Scrolls Online - No SLi Support // SLI supported for some time, scaling is variable depending on the zone/area/gameplay type. Heavily CPU bound. Personally worked with gamers on this board to refine profile.
Alien: Isolation - No SLi Support // SLI supported since launch. Another set of bits scales better beyond 19x10, but using in-game options you're unable to fix the shadow glitching that occurs when using them. That can be fixed through config file tweaks, but we cannot assume a player has those tweaks enabled so we have to support what the majority of players will use and the in-game options.
FIFA 15 - No Sli Support // Engine incompatibility
Dark Souls 2 - No Sli Support // SLI supported for some time. Personally worked with our team to develop this
Watch Dogs - No proper Sli Support // SLI supported since launch
Dead Rising 3 - No Sli Support // Engine incompatibility
SLI remains the best multi-GPU solution, in my opinion, and it's going to be the definitive solution for VR gaming thanks to VR SLI, which uses 1 GPU per eye on a headset, and applies other tweaks that dramatically reduce latency.
Hopefully this post addresses some of your concerns and gives you more visibility into our processes.