In BFA it was stated that these dungeons were designed for Mythic+. This trend can only be assumed to have carried on into Shadowlands, however both of these expansions have been very restrictive in how you approach the dungeon from a Mythic+ standpoint in comparison to Challenge Modes and Legion M+.
The paths are very linear and in some instances, you go over mob count by following a strictly linear path.
The choices you actively make as a group are not impactful if you are over mob count by the end of the dungeon. You have no choices if the path is strictly linear. Where’s the player creativity? It’s an option of what to skip rather than what to pull.
If we use some examples from this expansion:
Theatre of Pain - You’re always going to be over mob count here unless you play creatively and abuse some mind controls and skip the first pack.
Spires of Ascension - One path of the dungeon is easier than the other, so why would you ever use that path.
Plaguefall - You had some options to skip naturally with certain pathing in the dungeon, but they were removed with added tentacles so you were forced down a linear path.
Halls of Atonement - The mob design in this dungeon forces you down a certain path on higher keys. You simply don’t have enough kicks to handle most of the packs (yet wicked bolt was buffed), but there is a path that has limited casters which are manageable so all of your flexibility is removed.
There are also examples of requirements being placed in dungeons to engage with an event:
De Other Side - The door to Hakkar requires the final pack to be killed, which means you need to always do that pack.
Necrotic Wake - You must clear the entire necropolis.
Mists of Tirina Scithe - The maze requires the pack to be dead before you can interact with it.
We have a new problem created in Shadowlands Dungeons where checkpoints are either non-existent or placed in the final sections of the Dungeon which lowers their value.
In addition to the above have issues lingering from previous expansions where some mobs require so much commitment to kill but then reward you with next to no mob count. In BFA this was very noticeable in Shrine of the Storms, we can see this in Necrotic Wake this expansion with the Gatekeepers.
Huge open areas, better mob % balance, alternate paths allow you to experiment with different pulls and routes. If you want you can follow a linear no skip route. If you want to be more efficient you can pull big and then skip. You can be creative with pathing to avoid certain areas. The theme is that there are options.