You still get some balance from the lime juice and Cointreau while making the cocktail more of a way to showcase good tequila. I've always felt that the trick to a good cocktail is quality booze and not a lot of other stuff to drown it out. Same reason I'll use a 4:1 gin:lime ratio with gimlets.
Drinking tequila straight works too, though scotch or armagnac tends to be my spirit of choice 80% I'm drinking straight alcohol.
If I want to showcase good tequila I would indeed serve it neat. If it's tequila good enough I want to "showcase" it I should not need to add mixers to it for balance.
Just my opinion; drink whatever you like, however you like but I think there is a cut point where quality tequila (or any aged spirit for that matter) is best served without mixers.
Gin is not (99% of the time) an aged spirit so does not fall into this conversation on an equal basis.