...As per "Indiscretion"?
An imperfect defense, but still better than Starfleet's nothing.
...Yet it is a valid approach to choose nothing over grossly imperfect, if there are penalties to wearing the grossly imperfect (extra weight, hindrance to movement, looking silly). Cardassians might have been dealing with weaker beam weapons in the recent past, making their definition of inadequate less damning than Starfleet's.
I like the "partial dissipation of death ray blasts" explanation for all the types of armor we see, but none of them seem to do any good against concussion, shrapnel, or bladed weapons. Perhaps the ability to dissipate phasers is fundamentally incompatible with the ability to stop knives or bullets? Perhaps an effective armor against phasers needs to have the consistency of particularly foamy styrofoam?