RR
I think the shorter rods have some merit for the use you described.
The shorter sticks really increase your accuracy. I fished bass a few years ago with a buddy who is into it big time.
Some of the pinpoint jig casts he made wouldn't have been possible with a longer rod, at least in my opinion.
I think the same would apply for salmon fishing with a shorter rod.

WC,
Another reason for the short bass rods is they limit rod length to 8' in the major bass tournaments. There are a number for companies now producing short fly rods so they can be used in bass tournaments.
They've become very popular for saltwater use when fishing in tight quarters around mangroves where accuracy is really important.