One has to use bridge for one main reason (and there are a few minor reasons that are somehow advenced and I’m not going to mention at this opportunity): if you want to create a L2 (ethernet) network from multiple ports (can be ethernet interfaces, wireless interfaces, EoIP interfaces and a few more types). Bridge then moves frames between member ports without regard to higher layers (L3 is IP, L4 is TCP or UDP, …).
Essentially bridge is something like an ethernet switch.
Now, if you created a bridge and added a few interfaces to it, then you don’t configure anything else directly on those interfaces (not VLANs, not IP addresses, not PtP tunnels, nothing). You use bridge interface for that.