>But as mentioned index and ranking are inextricably tied together.
I'm pretty sure they're quite extricably tied together. I'm almost certain google's engine weights the different ranking variables (e.g. page speed) differently depending upon context. Why not expose those variables to other search engines? Well, it would kill google's search engine dominance - if you're concerned with that...
Unbundling isn't technically infeasible and it would create more competition. This would help with the arms race alluded to. What if another search engine used google's index to build a more spam free index? not good for google but great for Joe public.
>Motivation: If search is open and you therefore can't directly profit from your efforts to improve it (because you automatically give away anything you create to competitors) where is your motivation to keep innovating?
Nothing saying that they can't make money from the users of their index just as Bing makes money from DDG. However, is there any reason their search engine shouldn't compete with other similar offerings? Maybe somebody out there does it better.
Well, other than "we've got an unfair advantage and wed like to keep it please"
>It's harder than you think
Actually it's probably a LOT easier. This idea is a direct attack on google's power and the easiest response they can make is "too difficult. not possible". Not "this would fuck us in the bottom line". Simply "we can't do it, who are YOU to tell us it's possible? "
fwiw if you look through history similar reactions were made to attempts to regulate pretty much all utilities. Then it happened. This kind of response is kind of an expected part of the process. Most recently it happened in the UK when utilities and banks were told to open up API access to their data. Same claim you made.
Part two is when they tell you "it's not fair!". It's coming.