Humans are such visual creatures. Take away big eyes (baby seals) and fur (most mammals) and often what is left is the ick factor.
Not many creatures have a bigger ick factor than the spider. It seems like the more legs an animal has, the more alien it appears to humans. In that regard the centipede and the millipede have spiders beat. But spiders also have multiple eyes, and poison fangs: the words "poison" and "fangs" being enough to send any creature to the top of most folks' ick list.
Inhabitants of the U.S. and Western Europe have enough issues dealing with spiders of modest size. Those of us who dwell in the American Southwest can speak of silk-spinners boasting considerably more impressive dimensions. You have to go to the tropics of the world, though, to find the size champions of the spider world. Spiders whose legspan easily exceeds that of your open, spread palm. In contrast to the majority of popular feelings they regretfully inspire, these rainforest denizens are often startlingly beautiful.