My take on this is that they may or may not be synonyms, but they are definitely NOT interchangeable.
Think of "do" and "make" in English. Are they synonyms? Kind of. Or maybe not. But you can't freely substitute one for the other. They have their distinct roles.
Bugun yolculuz (or the correct 2nd person conjugation of yolculuk), why is it not enough? Is it just idiomatic to say make a trip? What about "I am on my way?"