Because it beats waiting an extra year or longer to apply simply because you have a couple more classes to take. I'll be done with co-reqs this year, except for A&P II which I'm taking in the summer, so if I get accepted all of my classes will be done. I applied for fall admission to my program. However, my program only accepts once a year. I have classmates who will need to take a couple classes while in the program if they are accepted, however they are willing to put in the extra effort of the added classes rather than wait an entire extra year to apply to the program. I've had friends in nursing school take co-reqs along with their nursing classes. It can be difficult, but not impossible, and they were able to get through them just fine.