but, you can do vibrato and tremolo without using the LFO feature of the PCE.   You can hear it in my Doom video, more towards the tail end though.  I think I did it in R Type too and and Shadow of the Beast, actually.   
   I don't use LFO.
Also, it's called a whammy bar 

 No one really actually calls it a trem bar.  Probably because it's wrong.  Blame Fender.  They sell their vibrato bridge assembly as a "tremolo", where other companies (Bigsby) sell it as a vibrato.  As far as actual tremolo goes my Ampeg had a real nice tremolo built in. That with my Gretsch made some real nice rockabilly noise.  
I tried to simulate a real fast tremolo in one of the Insanity chiptunes.  I think it was used on the green-robot level.  
Also, you don't mean to say LFO is useless in audio for music as a whole, right?   Just for PCE? 
Nat: Watch this if you want to see LFO in action 
The best way to describe LFO without being technical is done with one simple word
DEVO.