It's not just the "chance"of a sinking which is I agree not likely...although the chances ARE greatly increased if it blows up hard!... and it's an offshore Mooring...(like Tresco sound)
...again if your Rig is suitably equipped why would anyone take the chance...that's the whole reason to spec your Boat right in the beginning!...which is what the OP was asking about.
I've towed 1000's of miles as you know, never towed with trunks down and my hull bung VERY rarely gets removed..only dust in there!..(I never get water in the Hull) and that particular incident was real freaky weather and I put it in to illustrate a point.
To reiterate...I like Bilge pumps....(I've two)... Prefer autos,and wrote a few reasons why.
Now my feet are quite big!...Too big for dancing on the head of a Pin with you on every post.
...But maybe that's what Mods (of late anyway) do on this Forum