What I am more afraid of is people judging this device based on iPadOS 14... (overkill, limited OS etc.)
What other version of iPadOS has Apple given any of us to judge this device with?
I understand your point, of course. It's likely that any M1 iPad is going to spend only a few months of its life on iPadOS 14, and most reviewers should note that we can expect (substantial?) improvements in iPadOS 15, 16, etc over time.
But what the M1 iPad will arrive with is iPadOS 14, and until Apple announces 15 and its features, and gives reviewers a working version to assess its potential and eventually a final version to review the M1 iPad and release software as a pair, there's literally no option but to judge it based on what Apple sends out in the box.
If the product that Apple mails to John Gruber et al isn't good enough to stand on its own and be reviewed for what it is today, as-is, then Apple is making a huge mistake releasing it.
My 12.9" M1 iPad is due in early June, mostly so I can hand down my 2020 12.9 iPad pro to my wife so my daughter can take her 1st Gen 12.9 iPad Pro to college in the fall, so I've put my money down on this being a meaningful upgrade.