So why Shenron gave Piccolo a bonus transformation?

[Zelvin]

How, angels are above Shenlong’s power.

Well, to quote myself;

To be blunt, because it is still stupid, lazy and goes against character. Recall in DBS Broly, Goku stated that if Freeza tried to wish himself stronger, it wouldn't be by much. So a wish like that would be useless. SH tries to get around this by Dende just going "Oh I can just power up the dragon", which he can apparently do at any time without prep or explanation so long as he has a jug of water. Which means Shenron can theoretically be powered up indefinitely to the point you won't even need Super Dragonballs anymore. Which further breaks the limitations the Earth Dragonballs were meant to have.

Since Super Shenron can restore universes erased by the Omni-King, that puts Super Shenron above the Angels. And since apparently Dende can just power up Shenron whenever, there's no reason at all to believe Shenron won't become as powerful or close to as powerful as Super Shenron. Since there's no stated limit to how much Shenron can be powered up. So there's no reason to believe they can't just wish for people to be as powerful as Angels, just for them to then make that level of power irrelevant the same way they made UI and UE irrelevant with Melanin-infused Freeza.

[Aim]

How, angels are above Shenlong’s power.

Well, to quote myself;

To be blunt, because it is still stupid, lazy and goes against character. Recall in DBS Broly, Goku stated that if Freeza tried to wish himself stronger, it wouldn't be by much. So a wish like that would be useless. SH tries to get around this by Dende just going "Oh I can just power up the dragon", which he can apparently do at any time without prep or explanation so long as he has a jug of water. Which means Shenron can theoretically be powered up indefinitely to the point you won't even need Super Dragonballs anymore. Which further breaks the limitations the Earth Dragonballs were meant to have.

Since Super Shenron can restore universes erased by the Omni-King, that puts Super Shenron above the Angels. And since apparently Dende can just power up Shenron whenever, there's no reason at all to believe Shenron won't become as powerful or close to as powerful as Super Shenron. Since there's no stated limit to how much Shenron can be powered up. So there's no reason to believe they can't just wish for people to be as powerful as Angels, just for them to then make that level of power irrelevant the same way they made UI and UE irrelevant with Melanin-infused Freeza.

I mean, there’s probably a limit. As for Super Shenlong I don’t think it’s in Son’s character to just wish to go to that level.