This industry like almost all of them is full of competition with casinos that have been established for a long time in fact if you take a look you will notice that some of the longest running signature campaigns in the forum come from casinos and this is not really surprising because the moment you stop promoting your casino then another casino begins to take new players that could have played in your casino if you did not stopped the promotion.
Promotions/marketing is indeed vital for a casino to continue on growing their community. Signature campaign isn't the only thing to be considered tho. Funds should also be allocated in social media marketing and other website ads. One example of a well manage gambling site is primedice. They offer awesome promotions in a form where people needs to play in their site to get an awesome prize.
I haven't seen a casino does that yet. Maybe they should consider it, to increase traffic on their sites.