• The mind is usually considered a private area. Most people want their thoughts to themselves under most circumstances.
• Also, this stuff actually predates VOY; In TNG’s “Sarek”, Sarek is hesitant to mind-meld with Picard to temporarily treat his Bendii syndrome.
• On a random note, my history teacher had this as a poster on her wall:

*removed externally hosted image*

Because Tuvok, and the rest of the crew, esp Janeway, lacked anything resembling ethics or scruples.

Mind melds are like unprotected sex. Fine to be done with a trusted partner, not something you want to do a lot with randos