Free casino games are never termed gambling. These are the freebies that are offered by the casinos to try their platform before using any real money. Now when you risk your real and hard-earned money to win some extra money, this can be called gambling. Most of the time, these free games are provided by the casino to attract more users to the casinos. Hence, this is not gambling at all. Instead, this is a smart advertising technique, and you are the victim of it.
You're not far from the truth, some of the casino gambling websites uses that as attractions and also a test run method in their website, its a same vain whereby casino gambling websites gives a bonus, so I know that the reason why casino platform do such is to get traffic, let state this categorically, their is no gambling casino website that intend to do anything free, they have a motive of doing anything they feel like doing because they know that they most benefit in anything they do, I will say that their own strategies they applied to get customers, I think for now this is new initiative.
I have always said it that casinos never give anything for free, for whatever they give a player that they can not take back from that player, they will definitely take that thing (plus more) back from another player.
You see all this bonuses, promotions and rewards, there isn't anyone that comes without strings attached to it, online casinos are more and more of getting new gamblers, while they are also at the same time, doing everything to keep their current gamblers, and even wake up the inactive ones to start gambling as well.
I've read about a land based casino where if you win a huge amount of money, they would literally give you a vip suite in the casino's hotel area to lounge for free, this is to keep the gambler close and to constantly draw him in to gamble, this the casino will do until they are sure that they've regained back all the money the player won from them, then they can then ask the player to go home and take some really proper rest.
Every casino have a strategy that they use to take back from gamblers, what the casino has previously given to the gambler either in form of gifts and so on.