Yes I thought the same when I used it. We are using JsCache as a wrapper of any Js object or Js array to easily get/set properties. Maybe we could consider renaming JsCache (which initially was used as a cache class) to JsWrapper, JsOverlay or whatever makes more sense. 

I also think that we could expose some methods to the GQuery object although they are not in JQuery, since it makes sense to do something like:
String val = $(window).getProperty("something")
$(window).setProperty("something", "someval");
$(window).removeProperty("something", "someval");

This could be very useful to use GQuery to avoid writing jsni for certain trivial actions.