Re: "extending the process to include American citizens was too risky"
For a foreigner to get into the USA, they already have to complete at least one form (possibly more), be fingerprinted, and interviewed by an immigration official who is on average about as welcoming as Joe Stalin. All that after getting a visa to travel in the first place, which is where they demand access to your social media accounts.
I don't see anyone who's prepared to put up with all that making much fuss about a photograph. I've been avoiding the USA since 2002, but enough people don't to keep it in business.