When using either the quarterstaff or spear as a "Monk weapon", do you still gain the unarmed bonus action from Martial Arts if using 2 hands(1d8)?
On pg.78 of the PHB under Martial Arts it states that a Monk weapon cannot have the 2-handed or heavy property, so I assume since the versatile property is not the 2-handed property or heavy property then it does not matter if I use it in one or two hands. However, why then would a distinction be needed since the only simple weapon that does have the 2-handed property is a Greatclub, which is also mechanically identical to a quarterstaff used in two hands. Why make a rule that doesn't apply to anything?
The other interpretation is that you're meant to use 1d6 for damage in order to gain the Monk's Martial Arts bonus action, and using a 1d8 will forfeit the bonus because the quarterstaff is now considered 2-handed. Pg.147 under Versatile states "A damage value in parentheses (in this case 1d8) appears with the property—the damage when the weapon is used with two hands to make a melee attack."