Assuming that the glows points are DDS with pre-generated mipmaps, then it's the DDS converters fault. You can change the quality of the sampling used for mipmap resizing to something that works better and doesn't distort the image so much. With NVDXT I use the gaussian filter, which does quite well. If the mipmaps are created properly then they actually look pretty good, and you generally don't see any issues with them.
There are exceptions though (beam textures, some missile trails), but that is primarily due to code issues than actually being a problem with mipmaps. We don't really handle blending differently for anything, so it's a one shot deal. At some point I'll try and deal with proper filtering modes for different effects (for explosions, weapons, and things like that we need to use LOD bias rather than anisotropic filtering, for instance). But, crappy mipmap quality is generally to blame, and using box or cubic filters when making mipmaps has a tendency to suck pretty bad the smaller that you get.
