To answer your question "Why risk it?": To not lose more and more potential new users because they are annoyed by the huge real-time necessary to verify the current block chain with the official bitcoin versions.
It seems most people don't see this real danger -- this real-time behaviour might restrict (or even kill) bitcoin usage/spread seriously. :-(
You know what turns potential new users off of Bitcoin? Headlines like "Bitcoin hacked! Thousands lose all their Bitcoins!"
If having to wait ten minutes to an hour is what makes you not want to use Bitcoin, how about you wait until we come up with a overlay network on top of Bitcoin with instant transactions? It'll happen eventually; I'm working on one such concept myself.