I think that having a gambling license isn't a guarantee that the online casino won't scam the gamblers, but it's usually better to pick a casino with a license, if you are a gambler. The license kinda gives a false sense of security and the illusion of dealing with a legit business.
If you want to create a casino, try to get a license, otherwise you might have problems with the authorities.
Yes, having a license doesn't mean that the site won't do some shit in the future but the fact that they have a license means they might be serious about their business as they spend time to comply with that.
For me, I will not risk any money at those sites that don't have a license.
That's one of the factors that a gambling site should have.