The Atlas PIC for sure appreciated having a magenta line.. .. ;)

Absolutely! You simply say unable. If they insist you exercise your emergency authority.

OK, sounds about right

now for anybody, how often is that done for weather you have been vectored into?

Obviously we know where it wasn't done.

I'm not trying to find fault but just to get a feel for what actually is being done both on the ground and in the air.

Reminds me of my only time in Istanbul. Multiple crew, taking off northbound. Thunderstorm about 6 or 7 miles north of the runway at touching the edge of the first waypoint where we will make a 90 degree turn. Some flights are asking tower for an early turn with approval but that suggestion by me is ignored by the PIC. After all...we will just ask departure for an early turn.

It is so busy on departure frequency that we can't get a word in for an early turn. Only light rain encountered fortunately. Get the weather deviation clearance early.

Same happened to me going into a northern Italian airfield, a small CB that seemed to be on its deathbed (decaying) and did not paint more than just green was in our way, thus I thought I could enter that cloud on it edge. I judged wrong.
I judged wrong. Tock tock tock and the radome was due for repair. The TCAS was full in that terminal area.

If you're in climb or descent and under ATC what are you supposed to do with your own weather radar? Do you cancel your ATC instruction?

Agreed. Safety of the flight is captain's responsibility.

Thunderstorm about 6 or 7 miles north of the runway at touching the edge of the first waypoint where we will make a 90 degree turn. Some flights are asking tower for an early turn with approval but that suggestion by me is ignored by the PIC. After all...we will just ask departure for an early turn.

Was at a reasonable quiet airfield, but No.2 for departure, and luckily the taxiway approaching the Hold was pointing in take off direction. The sky ahead looked grey & unfriendly. We lit up the radar to scan the SID. Not nice. We called tower to ask Departure ATC for either; an opposite early left turn, or an extended climb out (across a national border) by 10nm and then the 270 right turn in the normal direction. All coordinated before we launched and stressless. Tower did not have radar and Departure was a remote location. ATC are a member of the team, but you are the captain/manager & coach, ultimately. Use all resources.

Did it about 2 days ago.

most often hail reflects radar poorly, it may not even display at all

The first pic of the Turkish Airline - any idea why only one half of the windscreen appears damaged? Pure luck, or a replacement part of a different material?

Transparent aluminum.

Be interested to see intakes/blades from the A320.

It has happened before and will happen again. As others have said on this thread, aircraft weather radar is not very good at identifying hail. See this:-
Incidents and Accidents

To me, this is the essence of the minimization of the risk encounters.

I tend to think along the lines that there is a lot more knowledge available from ground based radar, covering approaches and departures from an airport, than expecting airborne radar to key the crew actions.

For enroutes the expectations may be different.

I have seen many crews willingly fly into an obvious massive thunderstorm on approach, relying on previous pilot/ATC reports of 'it's just rain', or 'three aircraft in front of you landed successfully'. I am not talking monsoon conditions but obvious cells above the runway. Why risk it?

It might be 'just rain'. Then again, it might not. Or you might be the unlucky one to catch the first line of hail and lightning. Why risk it? The storm will move away in minutes.. And remember, the first one in the hold is the first one out. It takes just one 'negative request to hold at the IAF for the rest to follow'.

I have no idea what was painting on the wx radar in front of these Turkish crews, this is just my 2p worth.

I, like many others have a hard time believing that there was nothing painting on the radar. For this kind of hail you need a CB. A massive CB. CB's paint on most wx-radars I have seen.

But hey, I'm willing to learn.

WX radar is not good at painting dry hail which is normally at high altitude. It paints wet hail extremely well which would certainly have been the case in IST this time of year. In addition the radar will paint the cells that create the hail and in this case I understand the cell could be seen visually as well as being reported by ATC.
The dry hail issue being reported here is normally hail being spit out the top of a cell above 30,000 feet. Again the cell itself will paint however the hail can be tossed as much as 20 miles downwind of the cell and won't show up on radar until it gets below the freezing level and a film of moisture builds. This is the reason for the common advice to avoid enroute thunderstorms by 20 miles.

Sailvi767,
You are correct

Seems there are few depths the Ukrainians will not sink to.....

Ukrainian pilot cyber-bullied for landing hail-damaged passenger aircraft - PravdaReport

Errr. What was the option? Not land?

He isn't bullied for landing the jet or more generally for his skills but for being from the "wrong" part of Ukraine, thus not deserving of the praise handed over by the government.

Not that it excuses anything.