It will not cover 35mm format unless you put long tubes on it - the image circle is simply too small. If you put tubes on it long enough to cover "any other format", the focus point won't be outside the lens. Doesn't matter how much you love your 6x6 QG, this lens will either not cover your format or it will do so with the focus point being inside the lens body. It's not even certain you could cover 135 with it unless you use a teleconverter, which makes it a different lens.
30mm is quite wideangle compared to the 100mm and 180mm macros typically seen on DSLR systems, which is what this lens is designed for. The OP asked "why so wide?", which is a perfectly reasonable question because reduced working distance is generally seen as a negative. 30mm is the shortest macro ever made for the Alpha system.