I don't see anything wrong with wanting a new bike. More power to you and I hope you navigate the sea of what is out there and find something you enjoy.
But by all means... Keep that "ancient Miyata". I wanted a Miyata in the early 80s but never got one. I hope to some day find one in decent survivor condition local to me.
__________________
"It is the unknown around the corner that turns my wheels." -- Heinz Stücke