I still cannot for the life of me see a reason for a William's switch. I see no argument usurping the current status quo.
I see a reason for Hill saying it though, and it has nothing to do with Williams.
If we look at Williams engine history after the domination of Williams Renault in the mid 90's, we see that they struggled with Mechachrome, came back strongly with BMW(best f1 engine for a period of time), but BMW ditched them as Munich bosses were "
unimpressed with the continued lack of performance from the Williams cars".
http://www.pressetext.com/news/20030303036
They then switched to Cosworth for a season, Toyota for 3, back to Cosworth for 2 and then Renault for 2 seasons.
All the while slipping backwards and stagnating as rear to midfield runners.
They had the worst period in their history for a pointless streak, podiumless streak, and winless streak.
What should be underlined too, is that alot of this decline merged with a frozen engine formula where engines were practically at a level performance difference. Aero and Chassis were the differentiators in this time.
The switch to Brixworth has yielded results that belie Williams real problems. Williams require investment, and better facilities to be able to produce better chassis and aero concepts.
While Hill, and a few others here focus on the arbitrary, it is again worth pointing out what the underlying issues are.
And still, I don't see how Honda will not behave any differently to Mercedes or Ferrari in their supply. There is no guarantee that supply will completely equal, and given that
McLaren make the demands to the point of changing the size of components and their placement, any other customer will have to be second best.
This also should encompass that McLaren have Mobil lubricants, and any other supplied team will need to use a variant lubricant or develop their own, ditto the actual fuel.
I don't know if Hill has a book coming out or something, but his view here is lost on me. Had he proposed that Williams chase BMW again, or even Toyota, I'd see the sense. They'd be the first in line and recipient at source.