Of-course it is kind of risky. Though Annapurna or Everest base camp path is not closed but as I had conversations with lot of trekkers and guides when I was doing Everest base camp (this april)... all of them suggested NOT TO DO IT.
Yes , Because ABC trek is known for its beauty you get to see on the way this trek is not about summit but the journey as well so when it's cloudy you won't get that clear view of that huge magical beauty .
I went to a trek last year and was unable to see anything on the main day due to heavy rain I had to return with disappointment. And yes it's not safe as well the trek can become more exauasting .