It normally is to some degree, not all frames will accept all sizes of rotors. There's normally a good chance you can go up at least one size in rotor though.
For me, I think the biggest theoretical advantage is the hub flanges can be further apart, making for a stronger wheel. Given the huge numbers of folk riding round on multi-speed freehubs without their wheels exploding into fiery death, I'm not sure it's a deal-breaker.
https://www.gov.uk/government/ministers/parliamentary-under-secretary-of-state-for-the-future-digital-economy-and-online-safety
Looks like it might be Baroness Jones of Whitchurch? Though it also seems to be a subject that sits under both DCMS and the Home Office.