Either your hardware is too weak so there is no reason to ever turn it on, or it is strong enough that there is no reason to turn it off.
Shader options are only available if your graphic chipset is in the intermediate range where you would get acceptable FPS with shader options on, but you might prefer to turn them off anyway to make the game smoother.
On modern card GZDoom now assumes that shaders are universally supported without a significant performance hit so they can't be switched off anymore. This includes material properties like warping and brightmaps.
I have to admit, I too miss the shader options. I guess it's not a huge issue but I do like to experiment with things and to check out which shaders (etc) have what kind of impact on what I see. For example, the bright sprites bug I reported was affected by one of the shader settings IIRC and now I have no easy way to check that.
Also, although it may now be a non-issue, in the past there were certain issues with some shaders (warping flats for example could cause all sorts of weird effects) and disabling a single shader could perhaps still be a desirable option if such a situation arose again.
Most of the shader based problems were directly caused by the old shader code that no longer exists.
All the problem code was completely replaced by the rewrite in the summer.
Regarding warping, the only difference between a warped and an unwarped texture is that now different shaders are being used. In fact the shader is 90% the same, only the texel getter function is replaced.