Yachting as a pastime was well established on the East Coast long before the West Coast was widely settled, so lots of old money passing thru generations of sailing families until someone decides to spend his inheritance on starting a magazine.
From my experience at Cruising World, where most of the content was written by freelancers "out there," the published articles represented the material that was being submitted. Because the mag was based on the East Coast, and with that the perception that it was East Coast centric, the editors tried to cover the other regions as well as they could.
Part of the West Coast's problem, at least as we see it from this coast, is that the cruising grounds are not as extensive. Between New England, the Chesapeake, Florida, the Bahamas, and the Caribbean, there's a lot of water to cover, and a lot of people out there covering it. Fewer cruisers were sending in stories from the West Coast . . . CW had only a handful of contributors there and bucketsful doing the Atlantic and Caribbean.
Another point . . . the national mags that have survived -- CW, Yachting, Sail, Blue Water Sailing, Woodenboat, just happen to be on the East Coast. What happened to the West Coast magazines? Or were there any? Sailing (the mag) is from the Great Lakes . . . where the season is even shorter than in New England. Go figure.
BTW, I don't think any of the mags are enjoying anything like the income they had in the 1980s and '90s.