Hmm to be honest I already had this feedback, but I'm a bit stubborn

I understand your doubts about these skeletons, but I would like to have a more
subtle way of destroying ships than just breaking all the connected blocks. Two visually identical ships could have a different structure and be beaten different ways, finding their
weak spots. I think gameplay would be more interesting and I'd like to explore this way.
So how could the player know this structure & find the weak spots ? The thing is to find a rule so structure is obvious for the attacker.
- I could display/orient the graphical blocks depending on where they are attached, or add some overlay (like the debug arrows but with nicer graphics).
- Maybe a display mode
laser scan could display ship structure for a short time, and so player could find the weak spot
I like this oneIf all this doesn't work (from a gameplay point of view), I will switch back to another way of connecting parts. The one you suggested, a 4-connected could work but is more classical. I could also test a 2-connected approach, or 3-connected... Just have to find a good rule. This won't be a lot of change, as the structure algorithm is not merged with the destruction algorithm.
I just thought, maybe some blocks could be 1-connected like now, and other
special blocks 4-connected, and thus bring a more solid structure to the ship ?