Well, if the search function works as it should or if you just type the first closest letter of that instrument/FX name, you can find it really quick in the left browser. Let's admit it, in FL11 when you rightclick a track in the pattern window and select "Replace", then you pick up the instrument by searching through your VSTI-only list, but that means a few steps to be taken of adding that instrument, while in FL12 you just have all the instruments (and FX) right in the left browser and you just load it up from there without going through any "right click" steps or anything.
To me, VSTIs/FX loading feels faster on FL12. Now probably it's a matter of workflow for anyone that uses FLStudio as their main daw.

Regarding the .jpeg background replacement thing, probably they didn't just remove it, maybe they were forced by the vectorized concept to give it up.

 

@ Gramofon try this for Kontakt ,
in the wrapper settings / use fixed size buffers ( for buggy plugins)
for some reason it makes Kontakt work alot better for me anyways wort a try,
they messed it up in the beta version but its working ok in 12.

also there is a vid out about sorting out your plugin database its a the end of the page.

http://audiosex.pro/index.php?/topic/18307-fl-studio-11-3party-plugins-data-base-sharing/