Singing teachers do like to push you up towards the top of your range. In classical choirs, there's always a need for lots of high voices, and the tenors and sopranos get most of the best leading roles in opera etc, while basses and altos have to play the villains and the old bats. I had some lessons for a while, and the teacher used to say, "You know, you could have been a soprano!" as if this was a missed opportunity, whereas I had simply no wish to sing soprano; I think my lower register has a warmer, more natural sound.

The fact is that in folk music, most people prefer to sing (and to listen to) songs that are closer in pitch to the speaking voice, and singing teachers may not take this into consideration.

However, I don't think it does any harm to learn to open up your voice and extend your range. It may result in a better sound throughout your range, and it certainly won't hurt. It will just give you more options.

You'll need to experiment a bit more and listen back to recordings of yourself to choose the right range for your material and the settings where you sing. Fixing a key towards the top end of your comfort zone will probably help your voice to carry better, but there's no need to be coerced into the choirboy or operatic-tenor range if you don't like the resulting sound.

Marje