I think this advice really depends on each hackathon in particular. I've only gone to hackathons at my university, and I haven't found that good design is enoug

I think this advice really depends on each hackathon in particular. I've only gone to hackathons at my university, and I haven't found that good design is enough or even necessary to get first place. In fact, the first-place projects I remember had fairly poor design and won because they were impressive technically. Of course, really beautiful apps that were far less impressive technically did place, but only second or third. The first-place winners I remember were: a program that synced lyrics to music automatically, a distributed computing framework for JavaScript and a rather accurate face-recognition system. All of these did not have beautiful (or, frankly, even passable) front-ends, but were nontrivial and rather interesting from a CS standpoint. Moreover, this is not because nobody had good design--there were certainly very polished apps, and they even often placed second or third. They just never won first place at any of the hackathons I've been to.