According to Rosenberg's piece, the Flood Control Act of 1936 encouraged developers and residents to build buildings near the River that fail to provide clear views or easy access.
The law provided funding and philosophy for a capture and concretization of the River that still persists today.
Ride the bike path through Frogtown or walk it along the west side of the Elysian Valley, it's hard not to agree--the lofts, homes and light industrial spaces along the River look mostly at the hills.
You can read the full piece here, which includes Glassell Park resident (and CD 13 candidate) Mitch O'Farrell on the act and his relationship with the L.A. River.