I don't believe advertising creates a need. More like it creates curiosity and a sense of urgency. The difference is subtle and, I admit, kind of semantic. Think of it like sex – you already know what you like and dislike. No advertising is going to change your orientation. However, a good ad will tap into a need you already have, even if you haven't acted upon it yet. Someone attracted to the lure of gambling will more likely try online gambling if the ads make it seem fun, easy and accessible. Someone who doesn't like gambling is unlikely to care and may become turned off by the constant ads.
Online casinos are creating some new gamblers, but I'd argue they've seen plenty of ads over the years and were already... um... 'gambling-curious'. I'd guess most new customers come from existing gamblers who switch brands.
FYI, coffee served at acceptably hot temperatures will still cause 3rd degree burns, it'll just take an extra couple of seconds. I'm not disputing the judgment, just pointing out the margin for liability was very narrow and could've easily gone the other way if the defendant wasn't McDonalds.