This will never happen
I’ve written some words on the progress of things in another thread. Improved search of all kind (your references, full-text of PDFs and external databases) is part of our long term strategy. Also Jirka posted a quick intro, he is our new database and backend engineer working on search infrastructure.
I would like to see Full text search too
I have been using pdf managers for some years. I was just about to start with Paperpile, when I found this thread. Full text searching is the most basic function for a researcher. While you have many other sexy projects underway, all pale in importance to basic text searching. I encourage you to do some focus groups with folks who use these products to better match your development priorities with the needs of your potential customers.