There was an issue on the issue tracker that asks to remove it -
It was merged to a "decide what to do with this" issue instead -
I guess plans were not discussed yet. So I do not think you will get an official answer at the moment.
(I am building on this API a bit right now, but it is sort of a bonus feature that does not work so well anyway and that I will be fine without)
Regarding non-Chrome usage of this specific API - while it is indeed possible, it is not allowed and illegal. If you use your own API key, it has a low quota (50 requests per day or something) that cannot be increased. If you are using the API key of Chrome, well, it is totally illegal and you probably cannot based commercial products on this.