Your card supports the full featureset of DirectX 12. The one feature that people criticize the 900 series about, async compute, is something that adds performance, but it doesn't take away anything. That's a key difference. With your GTX 980 Ti, you don't really need a boost, so it won't matter.
On the flipside, your card can do several DirectX 12_1 features that have yet to be exploited in games (conservative rasterization and raster ordered views). Not all cards have these capabilities, but the GTX 980 Ti does. These have the potential to offer enhanced graphics and realistic lighting in games.
So, the bottom line is it's way too early to declare one architecture better than another. And no way you should be feeling bad...