Microdetail is not visible in the first image of this article. But What micro detail does, is keeping the magic ON when you inspect surface up close:
I used my Playtime Painter to combine a bunch of maps into one.
Using detaI maps is relatively performance friendly addition, texture sampling is the one taking up the most time. By packaging up to 4 masks into RGBA texture you reduce that up to 4 times. Also it's a good way to overcome the texture limit. Sure, in some cases you may want to have different tiling and/or offset for different masks, and also different combinations for different materials. But I think ideally a group of detail maps will represent a certain surface, maps will compliment each other : if there is a scratch, it is represented by gloss, ambient map and diffuse textures. In the image above it is not the case actually, I just combined 3 random maps that have nothing to do with each other.
Detail maps often used for a color texture, but I try to stay away from that approach because it will have the same effect across the entire plane. What IMHO is better are the above mentioned masks, which interact with light - their tiling will not be visible because they are showing up differently at different angles. Also in the image above, the gloss map is only visible where the base texture is already glossy.
Most games do use detail maps, and, as I know, games like Star Wars Battlefront 1 & 2 (most DICE games) have lots of texture Combining.