IMHO, periodic ATF changes are better than none and although Volvo says "no fluid changes required" in their books, even their instructors and reps advise otherwise to dealer people for those few, rare customers who want to keep their cars for a long time. Most new car buyers don't keep the same car for more than a few short years so yes, then the ATF will indeed go that distance w/o problems in most transmissions but not all. Do realize that "no maintenance" sells new cars as people are happy to hear that they don't need to do anything except drive. I've seen many 850 trannies last to around 150K miles with original ATF so that's not really bad considering but one would also have to wonder if perhaps the same trans would still be A-OK had the owner changed the ATF? We'll never really know.
I usually don't recommend ATF changes on 850s or FWD S/V70s until the car has about 60-70K miles as that's usually about when it begins to look dark in color. If it were my car, I might do it more often but then admittedly it's also easy for me to do and costs me nothing but my time.