From the photo of the Cessna, it looks as if the tip of the starboard wing was damaged, and likely to cause a lot of drag on that side.
However from the cockpit, the pilot could not have seen the full extent of the damage, and all he knew was that more left rudder input was necessary.
As to why the glider pilot did not use his parachute, sadly, even the AAIB may never be able to find out.
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