The one area where blockchain based gambling might offer a significant theoretical advance is games when all the gambling is contained within auditable code that's provably actuarially fair, but people generally don't get interested in slot machines because the ability to audit expected return is important to them (if they do, it's probably because they have a strong impulse to disregard that understanding and/or are gambling sums they don't care about...).

When it comes to bets on the outside world, crypto-gambling is arguably a lot worse than a high street bookmaker as it involves a de facto side bet on (i) the value of the crypto asset not declining during the bet duration and (ii) the oracle being reliable. It's not like you can't get odds or participate in more obscure bets or prediction markets using regular currency on p2p platforms or even with high street bookmakers either, it's just they're relatively niche interests...