I've flown SQ four times, I have to say I did note all the landings were very rough, several were land, bounce, land, bounce, over and over before landing and I too noticed a fairly violent zig zag down the runway on every occassion. Long before all this came up it was something I associated with the airline, so recent tragic events haven't influenced me.
I've flown a lot, especially around Asia and have to say by it's not a situation I've experienced flying airlines like MH, CX, NH, BA, AN in Asia at the same airports. To me that suggests it's an SQ problem, rather than one of their operating environment. But that's hardly scientific.
I remember during the LHR 50th Birthday Celebrations, the SQ 744 got lost, while flying in formation with about 20 other jetliners, on visuals using a motorway (highway) to navigate, through clear countryside, at about 3,000 ft, clear blue skies, between Stansted and Duxford Air Museum where the formation was due to conduct a fly past, a distance of 20 miles. I actually watched it, an Air Canada 762 flying behind quick followed him, while some planes kept going straight on, others sharply turned left, into the path of a DHL DC8, who'd just conducted a fly past, an Iberia 722 behind saw what was going on and took a sharp left to avoid, it was quite a farse, but quite nasty.
At first SQ said there had been a computer fault, later they said further investigations showed they were running late and intended to do what they did to save time.