Traveling to Nepal in August, should or should not ?

Well, end of August is still Monsoon time.
Since you have lived all over Asia, you will know what to expect then... rain, and lots of it. And somewhat limited visibility on a clouded day, and wonderful smells, just after every down poor.

On the other hand, because of the clouds the temperature is also not as high as it could otherwise have been during summer, so that's the pro side of the monsoon.

Furthermore there will be somewhat less tourists, somewhat higher discounts because of it being off-season, but overall the country is just as beautiful during the monsoon time as it is after (or before). Just a different season, not much more.

Well during the end of August monsoon season going to be end. This is the time where you can find greenery everywhere in Nepal as you have been to other parts of Asia. During this time the temperature of Nepal will be not to high not too low & visibility will be quite low. This is the off season for tourism industry in Nepal but you can take advantage of this season because they are providing their service on quite low price. In over all you can enjoy visiting Nepal during this time too.