I mean, firstly just that consumers hate having to plug in a ton of cables: it's bad for aesthetics, it's annoying to manage the cables, etc...
The bigger reason is probably to save board space as nvidia have been shrinking the form factor of the actual boards so they can dedicate more room to flow-through cooling. Connectors take up a lot of board edge.
The new spec does also have data pins so the devices can negotiate for power which could in theory reduce issues and inform the consumer better about limits with future PSUs and devices.
So there are advantages to the new spec, both specifically with the form factor and more generally.
The bigger reason is probably to save board space as nvidia have been shrinking the form factor of the actual boards so they can dedicate more room to flow-through cooling. Connectors take up a lot of board edge.
The new spec does also have data pins so the devices can negotiate for power which could in theory reduce issues and inform the consumer better about limits with future PSUs and devices.
So there are advantages to the new spec, both specifically with the form factor and more generally.