It is generally a bad idea to reuse passwords because when one site gets compromised, your other accounts are at risk too.

It is actually pretty rare for a site to get hacked so publicly as it did. A much more common hacking would be that someone is able to get ahold of the hashes of the passwords (or the plaintext passwords - if this was the case then the site would have extremely poor security) and then tests those passwords across various sites, hacking accounts very quietly. There are many instances of hackings when the fact that there was a hack was not discovered for several months/year+ (e.g. target).