I think the following are the 2 key questions that need to be answered:
😸 You can still get useless UVs on shields by crafting. There is no functional difference for UV distribution; you are not protecting us from getting bad UVs. We can still get Stun on a Plate Shield just like we can get Jelly Max on a Flourish.
😸 You cannot remove status UVs on shields from the game completely. Players will protest. So why not make them Punchable?

A: Yes, you can get UVs that are practically useless as well as UVs that are objectively useless through crafting. You can get a practically useless Jelly Very High on a Flourish. You can also craft an objectively useless Fire Max on Grey owlite shield. Punch always had the drawback of giving (mostly) bad UVs. A low piercing resist UV is bad, a fiend very high UV on acheron is also bad. Status UVs on shields are in a class of their own though because they are objectively useless. Any player who has the funds to roll at Punch, also has the experience to realize that a piercing low UV is bad, and that an acheron doesn't really benefit much at all from damage bonus UVs against fiends. So no player is going to actively pursue these UVs on those items. Status UVs on shields are potentially objectively useless but you cannot know this unless you have deeper knowledge of the game mechanics. Some status UVs on shields are very good and yes they cannot remove status UVs on shields completely because players would protest. But the difference between craftable UV and punchable UV is that a punchable UV can be actively pursued by unknowing players, while craftable UVs have a much higher barrier. An ignorant player is not going to craft 1000 2 star shields to get a specific status UV by accident, but an ignorant player might decide they want Fire max on their grey owlite shield and spend 2 million crowns trying to get it. And if they then find out that their fire max does nothing for them, they'll feel scammed. Someone who got a free fire max on the Grey Owlite shield they just upgraded isn't going to feel scammed. Adding status UVs to Punch would result in a lot of ignorant players rolling for objectively useless UVs and then demanding refunds that cannot be given for obvious reasons (refunding for ignorance would invite every con artist to roll on alternate accounts demanding refunds when they don't get a favorable roll)

Secondly, status UVs being punchable would also make it way more expensive for experienced players to try and get actually good UV rolls on shields (because on any given roll where you get a high/max UV, about half of the possible rolls would be objectively useless, and then a couple more would be bad. The way it currently works in the game, you have 50% chance of getting a good type with the other 50% being unfavorable or plain bad, but none of them are objectively useless.