And seriously (not sarcastically), what would that plan be?

First, the extra fuel burn is not that much. Assume a 737-400 is at 12000 feet when it crosses back over the top of SJC on the loop departure. Compare that to a similar flight doing a straight-out departure. If it takes 5 minutes to 12,000 feet, at 250 knots groundspeed it covers 24 statute miles. Both flights will hit top of climb (TOC) at the same time, still 24SM apart. The flight that did the loop departure burns extra fuel making up the 24SM gap but that's at efficient cruising altitude and airspeeds and takes less than 3 minutes. Assuming cruise fuel burn of 5500 pounds/hour that's 275 pounds or 45 gallons. (This is a highly simplistic analysis with lots of assumptions but in the ballpark).

SJC departures can't turn to the west due to terrain, or to the east due to even higher terrain.

A left turn above 10-12000 feet at OSI conflicts with traffic climbing out of SFO.

Offsetting to the east along the middle of the bay conflicts with SFO arrivals from the north and OAK departures. OAK and SFO are even more hemmed in by terrain and proximity. Don't forget there are several GA and military airports in the area too.

Unfortunately ATC in any urban area is a complex jigsaw puzzle...worse in the BA due to topography, lots of airports in a fairly small area, weather, and politics.

So again, what would you propose that doesn't cause a net increase in total fuel burned over the BA?