In my perspective, such activities also help to have people awake over the night to have things on watch, which is just one of the benefit of it. People may view it negatively but culture is behind this.
I don't personally participate with gambling activities during a wake. The practice in my family is to use the moment to have talks with the relatives who are most of the time away. But there are indeed different practices. I even witnessed some families who are having kareoke or singing activities during a wake and for them it is just to make things lively, as their way of reminiscing the one who passed away. But I agree, gambling activities could be a part of a family practice or culture, it just depends on how it will be done or the purpose behind it. Gambling in the first place is an activity for entertainment and the involvement of money just adds intensity and thrill with the outcomes. And with negative impressions, it depends with gambler's intention. As long as it is legal to what country it is being performed then things would be fine. If gamblers who will practice such activities in any ocassions would be doing it with sense of responsibility, it will be acceptable morally and socially.