Why should certain seeds be soaked?

[noorkhurshid]

   
Soaking seeds is a gardening technique for increasing germination rates. Soaking will benefit larger seeds, seeds with a hard seed coat, and seeds that are traditionally slow to germinate. Soaking seeds can also help with faster germination. Put the seeds in a bowl of warm water to absorb them. Large seeds, such as peas and beans, need to soak for 8 to 10 hours overnight. Tiny or thin-walled seeds can benefit from soaking for 1 to 2 hours.

[ETA]

I used to work at a restaurant where we would soak beans overnight to make black bean soup. 
One day, we didn't have time to make the soup after soaking the beans, so we waited until two days later. By then, several of the beans had sprouted and I planted them in my garden.
Those were black bean seeds, and I got beautiful green beans out of the deal :)

[SnowyDay]

I've absolutely never soaked any seeds and everything always germinates nicely.
I do freeze my seeds, sometimes even for long periods of time, like several months.