Hence, many DMs and players simply make the PC a member of his race, but with special characteristics (those which make him suitable as a PC) which are different from a typical member of his race.
If PCs of a certain race all possess or lack a certain characteristic, it is not a special characteristic. It is the common characteristic of the sub-population of a race from which the PCs derive. For instance, if a PC kobold lacks darkvision because he was cursed by a deity, and that is the standard for PC kobolds, then the game framework suggests kobolds are, if not frequently, then not infrequently cursed to lack darkvision by the gods. The PC version of a race should be "plug and play;" it should not only provide the balanced, PC version of the race, but the necessary background for incorporating them into a game.
Imagine, for instance, I designed a writeup for Bugs Bunnyans to appear in D&D. Bugs Bunnyans are anthropomorphic rabbit-like humanoids who can instantly disguise themselves, move with sudden bursts of speed, and have exceptional Charisma. They eat carrots and sing pop favorites. Imagine I do a pretty good job of balancing their special ablities, and the race appears in Dragon magazine. Yet the race is probably not suitable for most D&D games, whether as a PC or NPC, for reasons that have nothing to do with balance. The basic problem is that the backstory is problematic. Most D&D campaigns do not have animated cartoons as a player character race. So either I can exclude the race from my game, or I can adjust the backstory so that Bugs Bunnyans fit into the gameworld. By the time I have decided Bugs Bunnyans are not cartoon characters, were created by wizardry, are called Lagamorfs, and have a distant relation to Changelings... they are not Bugs Bunnyans any more. Whatever concept spawned their creation in the first place has (perhaps fortunately for us all) perished.
Nerfed PC kobolds present the same problem. As written, they do not belong in the game setting. There may be one kobold lacking darkvision, there may be several. However, writing up kobolds, publishing them sans darkvision, and saying, "Look, here is your kobold," is not a workable PC race because we don't know WHY they lack darkvision. Reasons can be manufactured by the GM and players, but the PC version of kobolds should explain why they are a viable PC option in the first place. There must be some darkblind kobold phenomenon of which they are a part. For most campaign settings, this is going to involve altering the setting to some degree. Perhaps kobolds commonly (90%+) qualify for darkvision but PCs must take a feat, perhaps being underground does it, perhaps there are "surface kobolds," but any of those suggestions involves, for any campaign that has already featured kobolds in any numbers, probably making some alterations.
Imagine there is a kobold city... is there a "dayblind kobold" section? Do dayblind kobolds carry lanterns and tin cups about? Do dayblind kobolds pay a tax for burning oxygen with their light sources? Are they a scorned ethnic minority? At least one of these things, or some other arrangement, would have to be true... and we have no idea, based on any published campaign guide, which of them is likely true. You might as well call them PC_Race001 as "kobold" because we don't know how they fit in as kobolds, much less the wider world.