Pilots often complain about workload so what happens when they have half a dozen pressure changes to cope with?
Most pilots will have one pressure setting to change, if you never get above the transition altitude then you may need to change, but a differential of 5hpa is considered to be irrelevant for enroute flight; so you actually only need to change when the pressure setting is greater than 5hpa from the original setting, you get aerodrome QNH from approach/tower/atis at destination. In Oz we use 'area QNHs' these are geographic areas of a couple hundred by couple of hundred miles. Sometimes there are multiple area QNH's for a particular QNH area, such as when a deep pressure front or tight low pressure system moves through. These are issued in a similar format to sigmets and are easy to read.
Personally I think it's a good thing to have a consistent base whatever you pick, FL180, is a good start and probably will help harmonize another aviation quirk. I Wonder if Oz will head that way too?
Wun Zero Thousand = A100. It is never confused with A070...