The core issue is actually JavaScript as I mentioned in another post. I doubt Google thinks this will ever change and they assume they'll never be able to deliver full Chrome on iOS. They provide the Chrome they do provide because one of the nice features of Chrome is universal syncing (of bookmarks, etc) between all your Chrome-running devices that you are signed into.
While Chrome on iOS isn't really Chrome, it does sync in to this so that your bookmarks, etc, work there just like on any real Chrome browser.
Firefox had a similar offering called Firefox Home on iOS which would sync bookmarks, history and even open tabs. It worked/works really well and I still use it. Mozilla, however, recently retired the app and made the source available on github[1]. The fact that Firefox currently has virtually no support on iOS is really frustrating for Firefox users in the Apple ecosystem.
While Chrome on iOS isn't really Chrome, it does sync in to this so that your bookmarks, etc, work there just like on any real Chrome browser.