They were big $$$$$ and clunky, yet they represented sort of a transition between electric typewriters and the dot-matrix printers.
It took a while to wean some people from using typewriters and calculators into computers, and DWPs were one way to move them.
Dot matrix printers were never a choice for business correspondence. I couldn't get a word processor into one of my old offices until the daisy wheel printers came out. All letters and specification had to appear professional and only character impact printers delivered. Other side of the problem was that copiers degraded legibilty of the already poor originals.
Transitions in office environs went like this: IBM Executive; IBM Selectric; Daisy Wheel printers: laser printers.
Line printers, small dot matrix printers were for in house drafts by techs, acct'g, basic back office stuff.
Covenantor, you were obviously in an advanced office, bypassing the DMP stage ;)
PS another reason for DPWs: the carbon-based "life" paper forms that would not work in DMPs. Like the Greeks, we were slaves to forms. Now, today, of course, we no longer use paper, everything is automated....
;)