Several points here and you are certainly entitled to your opinion, this is just mine.
Firstly, fish welfare is paramount, and I always, always, always put the safety of the fish before any captures.
There are two different types of leadcore.
The first type, like the Nash Limpets or the trout type leadcore, has a close weave and I would suggest is better for the flanks of the fish than straight mono.
The second type, like the Fox and Gardner stuff, is pretty much like ordinary braid (Silkworm etc) except that it has a soft lead inner.
With the lead stripped out at the hook end, then this is no different to something like Silkworm for a hooklength and so I can't really see any issues with using it for that, although I wouldn't use it behind the lead.
I hope that clear up the two types of leadcore and when I would use both.