My own view of the 139 is that it is a robust reliable aircraft suffering from the success of Agusta and regulator marketing - that the biggest possible engines in the smallest possible airframe will save your day. Doha crash -(non)pilot error, Spanish crash -pilot error, Korea crash -pilot error, China crash - pilot error ( until we hear otherwise from Agusta, hint: low alt 1.5 km from shore), Malaysia crash-pilot error, losing a couple of tails in Doha -pilot/maintenance?
Even where there has been a significant mechanical issue like in Hong Kong harbor, a skilled and trained crew was able to use the remaining aircraft capability to execute a safe landing.
Might be time for the industry to focus less on an engine quitting, which is almost nonexistent, and focus more of the available initial and recurrent training time on situations that actually have some risk. Of course this is counter to the notion that a pilot must be spring-loaded to deal with an engine failure on every takeoff at the worst possible time but that in true ETOPS fashion the second one will never quit. Beyond logic.