Why, they merged Big guns with small guns. What would be the negatives of merging melee and unarmed?
The negative is that merging skills (any) reduces the ability to specialize. Consider that now you cannot create a sharpshooter who is not also a minigun expert. Merging Melee with unarmed would then mean that one could not create a defensive Martial artist who was not also a knife expert ~and a sword expert, and a cudgel expert, and (adding thrown weapons) also an axe throwing expert. Now Fallout 1 itself lumped Melee as one skill, but the premise extends beyond Fallout and affects all RPG's that try to consolidate skills. :rolleyes:
Take First Aid & Doctor (now lumped as Medical). Originally First Aid was the skill for minor scraqes and cuts, while Doctor was for correcting crippling injuries (but could be used for simple healing). First Aid gave half the XP, took less time, and could be improved with books. Doctor gave twice the XP, took longer, and had to be pushed up with skill points (which took away from everything else, so Doctor was a deliberate commitment).
The end result of having them separate meant that PC's had a total of six possible heals per day, but only three chances to correct crippled limbs, and the choice to administer the appropriate treatment for their NPC's injuries. Medical retains none of that.