I certainly think it is worth having a set or two. If you haven't already, check out ar500armor.com (they always have 15-20% off on Black Friday)
In addition to the positives that Dolomite mentioned about steel plates, another big plus to me is they don't really require much upkeep/inspections/ or special handling. When I was in the military we had to have our ceramic plates x-rayed 2-3 times a year to identify any cracks or deficiencies. While I don't think anyone would ever intentionally drop their plates, I do remember it being common to find fractures on the bottoms and corners of the plates from them getting repeatedly set down too hard or tossing around in a kitbag. Nowadays I don't have access to an X-ray nor the $$$ to spend on replacing ceramics, so it's steel plates for me.
If you are not wanting to lock yourself into a designated heavy kit you could run a slick plate carrier with a "rack" setup over it to hold your mags, med kit, ect. That way if you don't feel the need for that much protection or need to go overland you could drop (cache) the plate carrier and still have your lightweightish setup to throw on.