This.If they know YouTube exists, they'll be able to find it in the browser (the website is already superior to the built in app according to articles I saw on the matter).
On every version of the iPhone, I've always gone into General > Restrictions in the Settings app and disabled the YouTube app. That way all YouTube links go to the browser. Then I access it via a browser bookmark, just as I do on my PC. You have the option of putting a shortcut icon on your springboard too.
The browser version of YouTube has always been excellent on iPhone. It's faster than the standalone app and doesn't have the limitations. You can choose high quality right on the video. I never saw a single reason to use the app version over the web version.