Training is extensive and regular re-certification is not optional. However, modern airliners are complex machines with many weird failure modes that rarely occur. Many of these scenarios are covered only occasionally during certifications since there is no chance to cover them all. Many of these scenarios never occur during a pilot's career but when they do they only may have seconds to take action. Instructors have to choose what to focus on. I'd say this is an example of something that slipped through as something worthy of focusing on.

IMHO the long term solution to improving safety is to make the pilots increasingly redundant. With the current generation of technology this is not yet feasible since they are depending on a wide range of technologies dating back decades. Also a lot of the planes flying are decades old designs. This makes them hard to automate and human-computer interaction has not evolved to the point where a computer can take over these tasks and deal with all the critical human interactions that are involved with operating a plane. In principle the problem is solvable, however. It's mostly just a matter of enough sensors and computation redundancy and improving communication technology to get humans out of the loop.

Mostly pilots these days take executive decisions that boil down to religiously following checklists for basically every scenario imaginable and programming the auto pilot to act accordingly. The auto pilot is activated right after take off and typically disabled on final moments before touch down; or in some cases after landing. Or as in this case, in an emergency.

That's not to marginalize their role. Flying an airliner is a two man operation and they tend to be extremely busy dealing with flying complex procedures, routing around weather, ad hoc queues from controllers, cross checking each other, etc. Most of that stuff requires pilots to have good situational awareness. Most of that awareness is created through reading their instruments, communicating on their radio, and looking outside (when weather permits).

All of that could be automated but it would require a complete rethink of how this business works. For example modern planes are basically equipped with multiple redundant computers and fly by wire control (i.e. a computer controls everything). Yet, critical information is passed to these computers via a non digital communications channel involving people trying to exchange crucial bits of information over a badly congested, low quality radio channel with limited range. This is a ridiculously convoluted, error prone, and hopelessly inefficient way of communicating. The only reason it exists is because agreeing and standardizing on something sensible is going to take decades and has taken decades already.

Most of the chatter on the radio is people cross verifying completely routine information. Worse, people on both sides tend to be very overloaded with information and yet lack the mechanisms to share information other than verbally. Controllers can be juggling communication with dozens of planes and pilots are bogged down in a barrage of instructions, complex procedures, and checklists. A lot of the training focuses on teaching both to stay on top of this (this is very hard). A lot of accidents result from their failure to do so. Emergencies are stressful and stress makes all this even harder.

So, a completely computer based system would do away with most of that to reduce task overload for pilots and controllers and ultimately reduce both of them to the role of remote managers that intervene by exception and very rarely. Ultimately such a system would run itself. Military drones are slightly ahead of the curve here.