More bolts = more holes. Less holes in a boat, the better.
Truly tragic and I feel for the relatives, friends, loved ones.
As an ex blue water sailor, faith in your boat is paramount and to have the keel tear off like that in the prevailing conditions at the time, it would have turned over within a blink of an eye, so even if they were all on deck, which they probably were as they had reported a water ingress situation, the opportunity to release the raft would have been very small. Scary stuff.
Impressive searching from the US, Canadian, UK search and rescue teams and the ARC boats and commercial shipping. Just such a shame that the find was not a more uplifting one.