I am surprised SIN-TPE-LAX even qualifies for 77W service - I would think the yields on TPE-LAX alone are lower due to a lot of competition (up to seven flights daily non-stop in that market!).

Think about it:
BR has up to 3 flights daily (flts 2, 12, 16)
CI has 2 flights daily (flts 6 & 8)
MH has flt 94

Lots of competition there...with a premium product like the 77W, I'd think they would want to focus on more profitable through-flight markets and leave the 777-200ER on SQ 27/28. But then, there may be more $$ in that market than we know otherwise BR wouldn't have 3 flights/day