In general, an easier weapon will start achieving hits and criticals at lower values. That's the same effect as giving the weapon a bonus. For ranged weapons, you could also put that adjustment in the range modifiers. A fixed bonus is safer than an everyman skill which will have outsized effects at high levels.
That wasn't done in the tables for RM2/RMC/RMSS/RMFRP. However in RMU, if you compare the crossbow table (i.e. light crossbow) to long bow, the long bow does more maximum damage but the crossbow starts hitting earlier. (Heavy crossbow does more damage than long bow, but both light and heavy crossbow start hitting at the same thresholds.)