More than 50% times where I choose normal difficulty, I instead play them on hard level.
Although it isn’t a burden when playing with a leveled character, it is a true burden when I want to start leveling a new character.
Please, solve it.
It is done that way intentionally. If system can’t match you with somebody with your chosen difficulty, it would search amongst somebody with another difficulty.
So, if few players currently chose Normal, and system can’t match you with “Normal” for too long, it would match you with somebody on Hard.
Fortunately or not, I think it would stay that way for foreseeable future.