I think most people agree that rugby teams are too heavy. Players are under too much pressure to bulk up, beyond what is healthy. Bigger pack weight does give a big advantage in a match, but it does not make rugby a better game.
There should be a maximum team weight. Maybe 1500kg for 15 players. Teams can still use very heavy players, but they must keep the total team weight under a limit. So being very heavy is a slight disadvantage for a player. The existing incentive will be reversed, to keep below a limit, to a healthier weight.
Very heavy players will still be selected, only if they are skillful enough to be worth keeping, despite the difficulty they create in keeping the team under the limit.
This does reduce the advantage very heavy peoples like the Europeans have over lighter peoples like the Asians. So it might be unpopular among supporters. I think it would instead make things more interesting. It would mean more teams can seriously compete in international events.
sounds similar to the pressures that make hockey players heavier. makes the sport worse but since its an advantage that is the direction it leans.
probably not enough players for weight classes to exist, but what if?
If weight classes existed, audiences would only want to watch the heaviest weight class. The best way is to keep one class, but still restrict the total team weight.