Ink smudges easily; toner doesn’t. It’s that simple. And the more committee members there are putting their grubby little fingers all over it, the more likely an inkjet-printed essay is to get smudged up and ugly. If you print your essay with a laser printer, it’s got a better shot of staying in pristine condition until the judging is done.
Laser printers aren’t nearly as hard to come by as they used to be. In fact, prices are coming down so low that inkjet printers will probably be extinct in five years. In the last six months, I’ve seen laser printers priced as low as $79. If you can swing that, pick one up for your home use, and you can use it for everything you write.