They aren't able to reduce the number of shown shader effects like that. They would need to completely re-write their graphics engine. However, they definitely want to add more video options to the UI, and they're always are working on effects and game events to improve performance. You should have seen the slowdowns with poison arrow before they changed the art.
It has been a repeated complaint that the rain in the Dominus fight and other places makes older video cards weep. They might give an option to turn off rain, or make the rain simpler or more optimized. I'm sure someone is working on that boss fight specifically.
Gentoo Linux ░ nVidia 343.13 ░ wine 1.7.26 (eroen)
winetricks -q vcrun2010 d3dx9_42 d3dcompiler_43 riched20 usp10
wine reg add 'HKLM\Software\Microsoft\Windows NT\CurrentVersion\FontSubstitutes' /v 'Fontin SmallCaps' /t REG_SZ /d 'Fontin'