minehole without pyre (bug or intended?)

[Kamekono]

Not sure if this works as intended, but you can build a minehole on the surface without requiring a mine pyre.

(IMO should be required there too. The soft ground is only the very top layer; the ceiling of caves is solid rock.)

[Vigilance]

This should be intended. This would be a painful and awful change.

[Mr_Bober]

This would be a painful and awful change.

How so?
Caves are no longer a rare sight, surface is literally spammed with them. So it wouldn't stop anyone from getting to level 1.

It would make it consistent. The only "downside" would be for those who use mineholes to raid an underground base to avoid sieging it. But considering they just made sieging harder, it would be consistent with that too.