Respond with a single big change Bungie could make, and I mean huge. Like player housing with a actual housing district none of this instanced stuff. Yes that means not every one would get "housing", however its that scarcity that makes it more desirable.
For me it would be dedicated servers w/[i]*kernel level anti-cheat[/i]. It would not just help address lag/latency but it would also make the game more secure.
[spoiler]*Kernel level or kernel based anti-cheat is a type of anti-cheat that operates at the deepest level of the system.[/spoiler]
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A total change of monetisation of loot and pinnacle loot. The best armour and skins should be earned in content, not bought.