Driverless printing became supported for various devices.
Did you notice that corresponding drivers occasionally provided extended print job settings?
Would you be looking for similar functionality after a switch to the IPP technology?
Do you observe any evolution with printer applications?
Yes, using IPP-based driverless printing typically limits the range of advanced print options available, especially when compared to model-specific CUPS drivers that expose full hardware capabilities. Proprietary/advanced print features may need driver support.
When a client connects to an IPP printer, it can send a Get-Printer-Attributes request, and the printer will return a list of available attributes including the following:
- Page size (e.g., A4, Letter)
- Color or grayscale
- Duplex (double-sided) printing
- Number of copies
- Media type
- Orientation and resolution
The above might be considered a minimum, and a given printer might advertise further capabilities, but the client would then also need the capability to handle the functionality (eg stapling, punching).
Is there a need to check if any features would be listed as attributes that would not be represented by (graphical) user interfaces like printer dialogues which I am familiar with so far? 
How much of such system functionality was supported by known drivers already?- Would you like to achieve any missing features by related “printer applications”?
Would you find a corresponding information source interesting anyhow?
I’m aware of that Printer Working Group reference already. I’m really not interested in discussing this topic further though, so unsubscribing. You can explore this for yourself.