If you run your drain line straight down I hope you realize that you now have an opening from the drain in the bottom of the refrigerator to the outside. I am not talking about insects but cool air getting out. The reason that the hose is routed out the vent is to get it higher than the drain opening. The water that collects in the "U" blocks the air leakage. I replaced my drain with 1/2 in rubber hose from Lowes. No more breaking. Ford's RV and Training has an entire series of videos on troubleshooting and repairing RV refrigerators. I recommend that everyone take a look at all of them. Number 3 deals with replacing the condensate line.
link and goes into detail as to why the hose is routed the way it is.