This would be considered SPAM... you the website owner, and even the software vendor, WebWiz in this case, may get in trouble for it with law enforcement agencies.
In my opinion it is better to leave it so it is only done when people want it. This is because your sever's performance, depending on the load it handles and how many posts are done daily, may drastically be impacted or degraded. The other thing is that we all get enough unwanted emails (spam) already... who wants more of it?!
[Edit]
I take that back... facebook policy is doing exactly what you are trying to acheieve. Whenever I comment on someone's status update and someone else replies i get notified (unless I opt out of receiving those notifications).
Edited by iSec - 22 November 2009 at 11:46pm