Only a open minded thought...
I use S&R with saved searches quite often. Something that you will never make as fast as with saved searches is block changes in a chain.
But this isn't the point.
I believe that you are capable to do fast copy & past actions, but I didn't see often people who was really fast with keyboards; not to say that the majority of users still won't have the capability to do this in the way you do it. So why should your experience work better for all? More a rhetorical question
It could have maybe also to do with a good setup for a workspace - having tools on a place where you need them and not clicking around within menu's. I often see people exactly doing this instead of taking a bit more time for thinking and then modifying the workplace in the way they need it.
I was quite happy when Kovid starts his work for the calibre editor and took as well a closer look to Sigil. He implement some of Sigil's good concepts as they was good and well developed from users who work with this tools on a day to day business. Saved searches is surely one of this. An other good concept was the flexible windows where a user is able to configure a workplace as he need it for his specific work.
For me it often looks like a lot of people don't know to use the capabilities of both programs.
I won't say that there is no space for additional little improvements, but the way it works now is (for me) way better than doing copy and past for S&R, es because what is with the rest of setup a search, combining searches for complex activities?