Was it just a rumor or did the EU laws stop Pokemon from having a real game corner?
I believe that is true. They changed the game corner because of the EU.
Edit: Just doubled checked and yup. The game's rating would have to be upped in Europe because kid games can't promote gambling. This resulted in Gamefreak just dropping gambling in their games.
It could also be because no one liked the gambling sections. Though the fact that it's closed in ORAS does give it merit.
We're not talking theories.
Did gamefreak really say they changed it because of EU?
Most likely. I remember in one game they changed the gambling in the EU version and after that it seems like they just said "fuck it" and dropped it in all versions.
That's not a confirmation, just speculation though. It was censored in platinum for EU, but HGSS which released later still had it. ---