@johnpoz:
If you bridged 4 ports together you would have a "HUB".. Since all packets seen on 1 port would go out all the other ports.. This is how a bridge works..
Not true with our bridges, they learn MACs the same as a switch and send traffic accordingly just like a switch.
The "use an actual switch" mentality is largely for performance reasons. People tend to show up wanting to use some Pentium III they pulled from a dumpster with a handful of crap Realtek NICs shoved in it then wonder why they can't push a gigabit of traffic between internal hosts. Firewalls aren't switches. In some limited circumstances, where you don't care about performance between internal hosts much, and require filtering between every internal host, it's a fine idea. People just tend to expect it to work the same way as the switch built into their consumer router, and it's not the same at all. Huge diff between multiple NICs in a firewall or router and a switch.