In contrast I brought a new ST4S in April 2004, and have had no problems that I would attribute to bad build quality.
Sure, the thing loses its back brake due to the fluid getting cooked by the master cylinder being bolted to the engine cases, but apart from that, no problems at all.
I have a 2002 998 too and on a recent trip lost the seat lock for the second time
The previous owner also told me it ate the cam belts at 1k miles
As others have said the bikes do need a bit more tlc and cost more to service than a jap bike, but imo give back far more riding enjoyment.