Now I'll tell you my version of it. Maybe I miss something or don't understand - feel free to correct me. MD2 is just mech, it have no bones, no lightmap, just polygons. As I told you, I test it on 2.2.1 - and found no problems, but the texture is just to bright. In 2.3 I have the same problem as you, but I'm sure that it no more bright than the texture! And that's it! But don't you think that the brightness itself is too high - look at the old body - it's glowing!
Check this out. I play a bit with gamma\brightness\contrast in game - model is fine and the texture is ok (all but alliace - wrong again in FlatTop.md2, last post of 2nd page. How did you make them?). Default brigtness is bad.
I did some research on this issue - If I got all my information right, the problem lies in how the python export script for Blender tells Blender the brightness of the texture, normal graphics used for the texture, such as Jpeg, TGA, whatever - they have a color value range for all colors (red, blue, green) of 0 to 255, total of 256 possible values.
The Quake MD2 format uses a range of 0 to 162, a total of 163 possible values for each color, according to some research on the net.
Somehow the color values aren't being converted or read properly, and as Migel said, the default brightness is bad, getting mucked up by the buggy python export script for Blender. I looked again at the python script, but, not knowing how to program in python, I can't make heads or tails of the code. I did find a line with the number "162" in the code, in a spot where I think the code is faulty, but I don't know how to correct it.
I have a feeling the faulty Blender export script isn't converting the color values between the two ranges (0 to 256 and 0 to 162) properly, which shoves the default brightness way too high. In other words, I think the python script is telling the MD2 to incorrectly read the texture, with too much brightness.
I'm attaching the Jpeg skin texture, as you can see the brightness of the texture in this graphic file doesn't look way too bright, this is how Blender creates the texture file in Jpeg format. I also loaded this Jpeg texture in GIMP and checked the stats of it, I couldn't find anything wrong or out of the ordinary with it.
Of course I could be wrong on many of these points, anyone is free to correct me, but this is my best guess.
Edit: Did some more research on the MD2 format, it contains a "LightNormalIndex" property, which I think is messed up because of the faulty python export script.