The requirement to reach the cursed skulls in every delve run is very detrimental to the overall delve experience. In most teams one or two players will rush out ahead of the group and complete the cursed skulls objective while the rest of the team completes the main objective. The rusher will then sit in the boss room, bored, until the main objective is complete leaving the team to complete the main objective while missing one+ member of their group.
In a team with bad communication, this gets even more chaotic. More rushers than necessary may run for the boss room leaving an even larger lack of damage for no reason. To make things worse some players rely on the movements of other players to determine their course. This can cause the group to split up randomly focusing everyone in different rooms creating a situation in which everyone gets a fraction of the loot from every run as apposed to getting the loot from the whole group if objectives were done while players are sticking together.
If the main objective is completed first then everyone just stands around waiting for the skip to boss room prompt.
No matter how you look at it, whether or not you're one of the players running towards the boss room, this is just dead air. It disrupts the flow of gameplay and provides no positive compensation. In challenge mode it can even directly enable people using programs they definitely shouldn't be (you know what I'm talking about) to gain an advantage over legitimate purple name competitors.
Removing this objective and allowing players to teleport to the boss room as soon as the main objective is complete would be a HUGE improvement to delves.