Afaik having visuals is the trip. How can you separate them? lol
Unless you mean no mind expansions etc, just pretty colours. In which case I would take some Valium or something with it, I heard that pretty much keeps it just a fun thing with no mind expansion. Although I wouldn't count on it.

Well why people might not want to take others first is because they last a lot longer and they could just as easily take a small hit of DMT to test the psychedelic arena. Makes more sense to me. And since acid is almost nothing like DMT, how would LSD prepare you for DMT?