Without getting into the pro's and cons that people have mentioned, and speaking as a player rather than a GM, I like the idea of the option of an instanced version. These things go in cycles. The MSR instance languished unused for a long time, but has started to pick up in popularity on Excelsior. Now it's at least 50/50 which version the league leader runs.
Each shard has their own way of running these two events, and it's up to the league leaders how they decide to run them. An instanced version would be one more tool for the league leaders to use if they wish.
Saying that, I don't know how hard or easy it would be for the devs to make an instanced version. They also have a lot to do so it's a matter of someone having the time to actually create an instanced version. It also might be an absolute nightmare to create.
Hami is the only one where multi boxing is forbidden. We relaxed the rule on MSR a long time ago, but Hami is a special case.