I think you're correct in that the 2D barcode is optional, since anyone can choose to submit a paper tax return through the mail using the forms with or without the 2D barcodes. The 2D barcodes increases speed and accuracy with the filing, according to the state, as you've noted.
That being said, the 2D barcode is only useful when mailing a paper return, not when e-filing. It is unnecessary if you are e-filing because no paper or PDF is being sent.
While it is optional, it would be in the interest of accuracy and efficiency to encode the 2D barcode on any printed state returns. Thank you for checking if it can be added back like in previous years!
