a problem that appears to be getting worse
Yes. No surprise there are practitioners encouraging people to access their superannuation for dental and cosmetic treatment. In addition, many consider it "their" money and combined with wanting to feel or look better.
Now if the Government in it's wisdom (?) decided to introduce legislation preventing access to superannuation for all these treatments except under extreme circumstance - which would be a loop hole which many would attempt to use - I would expect to hear strong objections from various quarters along the lines of "It is discriminating against people who require this work, is detrimental to their well-being and causing mental anguish, blah, blah, blah" and how cruel of Government to do this.
Always a difficult task to stand between money and a person's want plus pushing back against encouragement involving potential greed. Hands up those here who wish to give that a try.