One of the stupidest pet accessories...

[cichla1004]

Actually, the enclosures are not too small. Snakes are easier to keep and feel more comfortable in smaller enclosures. Most people don't want to put their snakes through the stress of being kept in huge area with insufficent sense of security.

However I have seen Ball Pythons in huge enclosures before, but the owners made sure they have a lot of hides (more than 20) of varying sizes.

I'm just speaking on personal opinion and experience here. I have kept many an adult ball python in a 6 foot by 2 foot enclosure with no signs of stress whatsoever. It's all in the way you set it up. Honestly a 3 foot ball can live in a ten gallon tank but is it really thriving. It will survive yes but is it happy... all a matter of opinion. (Not implying everyone keeps ball pythons in ten gallon tanks, just using as an example).
I won't hate anyone for keeping a snake in a small cage I for one just don't choose to do it. I also like to build huge display cages though. I like the way they brighten up the home.