Is it ‘ok’ to be one class only?

[ItMe]

just be a Dancer and just focus on getting really good at it and let it be my ‘thing’ would I be losing out?

No.
There is no wrong way to have fun.

Yes.
Playing other roles gives you a better understanding of the game as a whole and helps you better contextualize DNC.
Even if you just wanna dance you can benefit from a better understanding of what the rest of the party is/can be doing.