My reply, "It's not about you. It's about HER." He gave me a quizzical look. I explained...
When you do your (other) dances, you try to look good to your partner and to the audience... right? He (sheepishly) agrees. To do this you do the flashy multiple under arm turns, cumbias, the clothes, etc... right? Once again, he agrees.
Well, in tango, (as you can see) you really don't do that stuff (we were in a milonga). You're dancing so close that you can't look at each other.
You're concentrating so much on leading that if you try to showboat, you mess up your leading, making your motion choppy, awkward, and out of tune.
You can do the flashy stuff, but look at how crowded the floor is. You're liable to crash into others, so try to avoid it. Rather, do it when you have space. Besides, if you can't do it well yourself, it's unlikely you'll be able to lead it. If you try to force or teach her, you're just making her miserable, embarrassed or both.
In your (other) dance, you can do all this bump and grind and spin stuff because you're in one place. Here, the crowd is a densely moving herd.
What is important to dancing tango is the connection. It's that feeling of being "One body, four legs." There are two of you but you move as one—Movement comes from you, ending with her.
She is the reason why you tango. If you lead her to dance well, she'll be happy. With that, she'll look good, and you will be remembered positively. Don't worry about the steps. They'll come with practice and patience. Worry about walking properly first.
The bottom line, make every effort to make it good for HER. She'll appreciate that and you'll be remembered. That's what makes a good tango dancer.
He looked at me strangely and said "Ok," and walks off (I guess he was expecting me to teach him the super secret tango step combo). I chuckle and finish out the rest of the night dancing.