Not necessary.  They are really personal preference all the way around -- pro and amateur alike.  From what I see, most riders use stomp pads and there are sp many different kinds you are bound to find some pattern that fits with your style.

you can take em off but once you do they're pretty much worthless. as in every time you take it off you have to buy one. well most of em. i got lucky with my little metal spikes once and could put them back on.

as far as necessary, on some boards they are. my grudge is impossible to ride without a stomp. the topsheet is a polished clear coat and is slicker than ice. but my manual isnt nearly as slick so i can ride it without.  i use clear skateboard griptape on my grudge as a stomp pad. find out this winter if it'll work or not. its not paper so it should, and you cant even tell unless you're looking directly at it.