I don't really understand this popular comment. Why would your preferences in terms of how many beds are in your hospital room change at age 65? In other words, if you're planning to "downgrade" when you're older, why not now and save the money? Why are you paying extra insurance premiums for a level of care that you don't deem important enough to insure? Bear in mind an "as charged" public hospital B1 ward plan still lets you stay in A ward if you wish. You just pay a little extra per day from MediSave and/or cash, that's all.
Public Hospital Wards
A = 1 bed, air conditioned, choice of doctor (subject to her/his availability), attached bathroom, sofa
B1 = 4 beds, air conditioned, choice of doctor (""), attached bathroom
B2+ = 5 beds, air conditioned, doctor assigned, attached bathroom
B2 and C = 6 or more beds per room, natural ventilation (occasionally with spot cooling), doctor assigned, common bathrooms
These ward categories really don't make any practical difference in the ICU.
I keep dropping hints...

Insure against big bills (you cannot reasonably handle) for
necessities, not luxuries. Do you
need A ward? If we're being honest with ourselves, no.
However, unfortunately the Integrated Shield plan providers typically tweak their public hospital B1 ward plans so that they have other policy conditions that are not as robust as their A and private hospital plans. And foreigners (non-citizens/non-PRs) can't buy a public hospital B1 ward plan. So you might have to overinsure the ward class in order to get whatever other coverage provisions you genuinely need.