I suspect a big part of the reason that AF and LH offer such elaborate F ground experiences at CDG and FRA is that the J and Y passenger experience at those airports ranges from frustrating to eighth-circle-of-hell. SIN by contrast is fairly pleasant for all passengers. So F passengers don't get to feel as special, but it's not like one particularly suffers having to make your own way through Changi, other than the occasional long-ish walk.