6. Thieves also gain a second bonus action instead of second-story work, since there is no climbing, cunning action only works for Dash as Hide and disengange are bonus actions for every class, which makes the Rogue weaker in comparison.
Cunning action: Hide specially is one of the most iconic features of the class in the PnP.
You can use the second bonus action for a second off-hand attack, that's not exactly weak.
Not weak, but that's not how the Thief works in the Pnp. His second-story work and bonus sleight of hand are supposed to be used in dickish moves like hitting and climbing up a tree were an enemy can't reach you or use sleight of hand to rob an enemy of his sheated weapon. The thief in the Pnp is not a DPS class, Assassins and Swashbucklers do that, they are more about cunning and creativity.
This is an example of a fundamental mechanical change as the class plays very differently in the game compared to Pnp.