This trend is endless.  Hollywood shows no shame in resorting to it over and over again.  It's been pointed out to me that ALLY MCBEAL fell down relentlessly on the show, at least one of the Olsen Twins does it in New York Minute (fat chance I'll be confirming that one personally) and that Kate Hudson "comically" wipes out in Raising Helen.  Once again, all pretty girls and all in an attempt to humanize them.  I've got an idea, you want these beauties to be more relate-able to everyday girls?  How about having them gain about 30 pounds each.