Comfort isn't the main selling point. In no particular order:

• Versatile: indoor, outdoor, dry, wet,...
• Easy to clean
• Easy to take on or off
• Inexpensive (when on sale)
• Relatively durable/reliable
• Protects toes (unlike sandals)
• Many colors, styles, and patterns

I also used to hate how they looked, and I thought other people were just falling for the fad. But I bought some after literally being indoctrinated by my other coworkers at a summer camp, and never looked back. They are just such useful shoes that it really changes how you perceive them once they've worked for you.

P.S. Just in case you were wondering, there are still people at summer camp that continue to hate crocs, but they're aware they're in the minority :p