This has been suggested many times and never goes through.
If you want to get involved with RSGP gambling (which it sounds like you do), just wander over to the RuneScape 2 Mini Games & PKing section. There are tons of advertised dice clans, flower clans, etc. as well as people hosting gambling threads for other games like Runelink, Connect 4 etc.
If you head over to the sports section, I believe there are some gambling threads if you like to bet on sports games as well. Most of what you are suggesting is already readily available here