Sure "lack of equipment" is a good excuse to cancel an underbooked flight, but is this really the case with SIA?
I'd be interested to hear from anyone on this forum who flew an SQ flight that was less than 65% full, and indicate that this was regularly the case for the route they flew on.
As for reducing a/c turnaround at their HQ; ok even if it was operationally possible to do this, say 9V-SPwhatever is able to depart 15 min earlier, is there a slot available at its destination for to land 15 min earlier?
If the destination was PER, this would be not a problem, but SYD, NRT, CDG or LHR, etc probably would be.
Curfews and restricted landing slots at destinations often determine departures, which in turn may also be subject to similar constraints - so while utilisation of equipment may not be as high as the accountants would want, an airline has to juggle this with all the other parameters that make up a schedule.
IMO SQ, and CX, want a good return on the large investment they have made in their cabin systems. Most Oceania, and to some degree N. American, pax are advanced purchase tourists or VF&R, so to get their money back SQ & CX are now catering more for the now growing high yield SE & East Asian business pax market who are paying full fares. To do this they have to reduce some less profitable, but still well patronised, flights until their new a/c are delivered.
Yield and the bottom line rule, as always.
The following Star Alliance airlines also serve SIN:
Air New Zealand
All Nippon Airways
So Europe, N. Asia, N. America and NZ are covered, with ANZ also providing some limited uplift from Australia. Perhaps Ansett need to apply for rights to SIN from Australia?
Anyway that's my assessment for what it's worth.