I totally understand the feature. I'd try it in a heartbeat if it was possible. But it isn't possible because the two sides of Hive are not separate layers. They're one. Which is why they're on the same page and share their resources/modulations/signals. It's the inherent concept of Hive not to be multi-layered.
The arpeggiator and sequencer in Hive do exactly the same as a MIDI unit would. They send MIDI notes to Hive's voice manager. Those MIDI notes are transformed into gate signals and pitch tracking information. Each voice in Hive responds to exactly one note. If I add another identical sequencer or arpeggiator, I end up playing new voices, i.e. they can not trigger/play left side and right side independently, simply because left side and right side have largely overlapping functionality.
As I said, I "get" the thing about layers, but I simply dislike them.
I have a lot of ideas for dual/triple/quad sequencing/arpeggiating in Hive, but it does not involve transforming Hive into a multi-layered synth with fully separate parts. It involves stuff I learned from the modular world, which I find more fitting for Hive's concept.