Your print size straight out of the camera on the K-r/K-x should be roughly 60x40 inches @ 72dpi and around 5MB in size give or take. If you were to print it at this size and at this resolution, it would probably look like crap up close. That said a 60x40 print is probably not going to be made by the average person. You will probably be printing it at 8x10 (or smaller) in which case your printer will resample and condense the image automatically for you so you'll never notice the difference. That same image when converted to 300dpi works out to about 15X9 (ish) - which is more than what the average print would be.
What people are talking about when they say to reduce to 72dpi is 72dpi AND a reduction in physical size as well. A 15x9(ish) image at 72 dpi works out to around 500-600kb (more or less) - a good deal smaller and less detailed than the 5MB size you're seeing coming straight off the camera.
If your images coming off camera are wildly less than 4-6 megabytes, then you'll have an issue printing because you're losing data somewhere. If not, don't worry about it - you're looking at 72dpi, but its set for a wildly huge print size which you probably are never going to come close to touching anyhow.
EDIT: I worked a digital printers back in the day, so I actually know about this stuff.
Granted back then digital cameras were only just starting to come into play, but the basic guts of the whole process is the same. Also, if printing large format for signs or display on a wall, etc, you're probably able to get away with lower resolution anyhow since people will be viewing your print from a distance to take it all in rather than from up close, so the 72dpi print resolution won't really matter then, either.