I don't particularly think that Hobgoblins 'got the shaft', in terms of thier abilities: +2 dex, +2 con, +4 move silently is nice, and they don't have penalties to wis or int. I would consider playing a Hob character. I think that Hobgoblins seem less dangerous than Orcs for two reasons. First the designers min/maxed Orc fighting equipment, and gave the Hobs equipment that more or less min/maxed thier stealth. This is ok if you give the Hobs reasonable chances of surprising the party and let the Hobs have a tactical advantage (they are supposed to be cunning), but in a straight up fight you should give the Hobs more militant equipment.
I do think Goblins got the shaft, or at least that they were poorly converted from 1st edition.
If we give the Hobs scale mail and large shields, the AC of thier front line fighters rises to 17 (at the cost of making them clanky and unable to surprise). If we make 1/3rd of thier force archers with longbows (and better yet move a point of str over to dex and min/max the archers a little), suddenly the force becomes competitively dangerous.
The other reason is while the Hobgoblins stats are in line with traditional first edition abilities, the Orcs are not. Orcs never did extra damage on attacks due to strength. The reason that they do now, is that the designers wanted to justify the fact that a half-orc gets +2 str. This creates the odd situation that Orcs (tradiationally 1 HD creatures) now have better THAC0 than Hobgoblins (tradiationally 1+1 HD creatures use a better collumn on the table). One way to handle this would be assume that many if not most Hobgoblins (unlike thier less disciplined foes) are true Fighters, and give them 1 more h.p. and one Weapon Focus feat. This is in fact what I do, which returns Hobgoblins to the scariness that I feel they should have. However, many people have problems with making 'PC classes' common. I however make no real distinction between PC's and NPC's. All my NPC's are min/maxed within the limitations of thier attributes (an average NPC always has average attributes) and job profile (a merchant is min/maxed as a merchant unless I want him to be inept for some RP reason) and are played as cunningly as I think their intelligence warrants.
"...in most fantasy worlds, pretty much every hobgoblin (say) is a warrior, so arguably the Monster Manual hobgoblin is the equivalent of the human Commoner-1 farmer."
That's what I feel.
I'd like to point out here that I think that the DMG writer really dropped the ball in the class description of Commoners. He writes that in areas were commoners have to drive off regular attacks of Gnolls (or something like that) that they will have several levels (or something like that).
That's ubsurd. In areas were commoners have to drive off regular attacks of Gnolls, all the commoners are dead or fled as refugees a long time ago. In border areas, average humans are warriors just as average orcs and hobgoblins are warriors. So, in a border area, every male in the village (and maybe some of the women depending on the culture) is a War1 or War2 - just like the orcs, hobgoblins, and gnolls across the border.
The same is true of nomads, and possibly barbarian tribes, though I'd like to think that the average members of barbarian tribes are well - barbarians.
Commoners only become the common class in sheltered areas were combat skills are of little real value.
Likewise, I feel that in civilized areas, the goverment is capable of fielding entire armies of well trained Ftr1's and Ftr2's. Warriors only exist in numbers in areas were literate sophisticated professional training is scarce. I don't think that NPC's don't take PC classes because they have some enherent quality that prevents it. I think that they don't take PC classes either because they don't have the oppurtunity or don't need them.
It is for this reason I think it ubsurd to suggest that there are commoners, warriors, adepts, and barbarians (the illiterate classes) in Grey Elven society, given that Grey Elven society ought to represent the pinical of literate sophistication in most campaigns (that have Grey Elves).