It's not a bad idea. In that configuration, it protects your battery if the heavy gauge supply wire shorts, although that is unlikely. If anything after the fuse block shorts, the lower amp fuse on the affected circuit(s) would blow instead.
Without that in-line fuse, if the supply wire's insulation is compromised, your battery will discharge (regardless whether or not the bike's ignition is on) and it could possibly overheat, leak and/or explode.
Small price for some extra protection, in my opinion.