First, what is "NLC"? Never heard of it.
We lived in a leasehold flat in South London when I was a boy and my father continued living there as a widower until he died some 12 years ago.
We had no problems and I sold the flat with the unexpired portion of the lease with no trouble at all.
BUT
It was a privately built block with no service company, so there were no management charges. Expenses were split among the flat holders - each paid an equal share.
It was built in the 1930s so there were no cladding or insulation issues.
The ground rent was fixed (back in 1965) as £5 p.a, with NO increases. It was payable to the owner of the ground floor flat for use of the pathway to the back of the block.
Being leasehold was not an issue - it was simply a rented flat with the rent paid up-front for a given period.
The problem is not with leasehold per se. Rather it's with unregulated service charges and ground rent increases. These are what need to be controlled. Something along the lines of the Unfair Contract Terms Act?
(BTW our ground rent was payable half-yearly. My Dad paid his £2.50, in cash, to the guy in the bottom flat every 6 months until he died. And he got a receipt.)