The novelty/hype is because they're unapologetically actually wide enough for people's feet, particularly their toes, to spread out properly and for the wearer to have healthy biomechanical functioning.
You view them as ugly because we've been conditioned to think that narrow toeboxes and small, dainty feet are pretty and feminine and, as long as we can't actually see the results of wearing unhealthy footwear (ie, no visible bunions, blisters or collapsing insteps), it's attractive to wear shoes for the socialised gaze - I don't say male gaze because it's too deeply entrenched in both male and female.
Crocs probably get the strongest reaction (along with some barefoot shoes) because they aren't trying in the slightest to hide or disguise the shape - other more conventional shoes that have the right shape and width are often derided as being school shoes.
Think of how many people declare that feet are disgusting and ugly. Few say the same about hands, noses or eyes - but feet are as essential a part of the body as those. We have been conditioned to find a natural part of our bodies as repellent unless they conform perfectly to an ideal that bears absolutely no relation to health and function or are hidden to appear that way - and shoes are the natural extension to this revulsion if they indicate through their shape and size that we might have normal, healthy, functioning bodies.
It's very sad, really, to be socialised to hate a part of ourselves so much that it's normal to reject healthy footwear in favour of what damages us.