OK... so let's do an exercise about what that would entail so you understand why we don't port things back often:
Ratchet per step, at its most simple form, would require one ratchet param per step. Makes sense since it's a chord based polyphonic sequencer, not individual timbres.
If we conservatively say 2-8 ratchets we could get away with 4 bits per step. For a 64 step sequencer, that requires 32 8 bit params if we pack them. Since we didn't save room for params (because we were fairly certain we would not be adding large features due to the simplicity of the architecture) I didn't put unused params in the list, so we would have to expand it. The sound file would have be versioned and handled correctly. Not hard to do, we've done it on most of our more current instruments, but takes time when it wasn't baked into the code.
More importantly, what does the UI look like? Even if we could think of a simple way to indicate how many ratchets there are per step... how do you edit it on the front panel? How do you ratchet vs. no ratchet? Even if you can figure out a somewhat clean way of doing it this will feel clunky and un-intuitive. Not what the instrument is designed for.
And then the sequencer itself. It is low resolution, which means I would have to kick up the processor time and make sure that it runs smoothly faster to do clean ratcheting, at least 96ppqn. That would take a while. Anything over 24ppqn is a LOT more complicated because it runs faster than MIDI clock rate. That means you have to interpolate and run internal and external clock at the same time. That would take a while to port back to an older and slower processor. I rewrote everything from scratch on the Pro3 to handle all these new features, on a new chip, with a new faster OS.
How many extra would we sell? I can't imagine we'd sell any just because of this feature honestly, and we already have it working on new products so it wouldn't give us technology we didn't already have. As an economical decision it makes very little sense.
That's the short answer of why it won't happen on the P6/OB6
Sadly I've been told that the P6/OB-6 have "likely" been put out to pasture in regard to updates. The meaty P12/Pro 2 linear FM update will continue to be the shining exception and not the rule. 
My personal lockdown consideration vote would have gone towards a decent reverb, as the super-plate algorithm being transferred seemed feasible...
On another forum they said it's not possible to add the reverb. I think they will still do another update because they current one is still beta. I think they will do one more update and add some things. Racheting would be easy to add and would not compete with pro3. I'm not gonna buy that anyway, I have other synths too much in that vain. It's not like racheting is gonna turn the simple phrase sequencer on the p6 into a sequencing powerhouse.. it would just be a nice little fun added ability.
Whoa man no.. your making it really complicated. I already explained you can put it in the UI with no trouble, you already have hit back to erase a step right? So same procedure just forward and the note press to rachet, since a rachet is a forward step before next step.
Second, don't make it polyphonic, you already have triplets in the Arp right? Same thing, just one event(note) between next step. Only first note of a chord or single note, chords would sound messy.
Third, you should because it's main competitors already can.. super six and matriarch both rachet. Just one more in-between note would be huge for us and would compete better with the others.. another reason to go for this over the competition. I don't know about the programming but if you can squeeze even one note of rachet in, it would be really huge, prophet 6 is to good a synth to not have it, nomatter what comes from you guys in the future.. This synth is special, history bring created again I believe.. please, please, think about it!! No confusing ui, it makes sense. A killer feature too.