Mars, I completely agree that the reductions in helideck dimensions is not acceptable. Unfortunately this trend is not limited to the GoM.
My understanding is that this helideck size was so small is because it was considered Private; Prior Permission Required (PPR) and requires that the crew is briefed on the hazards. FAA Advisory Circular AC 150/5390-2A states that :-
"Elevated PPR Heliports. At PPR rooftop or otherwise elevated facilities the TLOF can be a minimum of two times the maximum dimension (length or width) of the undercarriage of the design helicopter..."
Having worked in the GoM recently, is sad to say that very few NOTAMS are issued to the closing of helidecks or hazards.