Marj, you are right-on!
But don't hold your breath...
I have worked with electronic imaging solutions since 1981 and at the outset of "Desktop Publishing" in the late 80's the language migrated from 'technically correct' to 'marketing cool', it would be difficult to reverse the trend now. It was more important for copier companies to communicate with corporate types than to conform to technically correct terms. This pre-dates digital workflow in photography by over a decade.
Follow the money and you'll find the answer.
Selling laser and inkjet printers into the office market was, and still is, huge business. Additionally, most graphics software is also geared to a less sophisticated (non-professional) market. Thirty-years ago presentations were created by graphic artists not office-clerks and sales-people, and it shows...
So, as long as there is money to be made, we will favour 'cool' over 'correct' and 'common' over 'correct' because no-one chooses 'correct' over 'money and acceptance'.
For those who might be interested:
DPI = the pitch or frequency of a print head in a laser or inkjet printer. It is not a measurement of dimension. It tells us the number of laser beam exposures or inkjet droplets used to image per-inch of image.
PPI = the number of pixels-per-inch in a raster image (tiff, jpeg, png etc.). Metric uses the term 'res' for lines per mm. e.g. 'res12' which = 304ppi.
LPI = "Lines-per-Inch" LPI referred to screen frequency for half tone images and graphics used to make printing plates and display resolution. For example, we print the photos in a magazine @ 175lpi which requires tiff files of 300ppi for ideal quality.
Enjoy, but don't waste time over this,
Stan