I'm looking at it from a visitors point of view. Compared to other countries the size of the plate is huge. As a diabetic, I leave almost half of it which I suppose I could take away in a doggy bag, but from my point of view, too much is as unhealthy as is too little. Plus, the prices are already generous and value for money.
So, yes a 10% reduction in plate size without a corresponding price reduction would be acceptable to me although I would prefer a half portion at a 50% price reduction.
"For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places."
Ephesians 6:12