We were at All Star Music in September and booked a preferred room. For the extra $75 a week... we found it to be SO worth it.
A preferred room at All Star Music puts you in building 1 or 10; the Calypso section. These buildings provide the quickest walk (less than a minute) to the main building and main pool. I understand your concern though, as we too spent the majority of our time at the parks.
At the end of the day, after walking on your feet for hours, waiting for the bus and the bus ride home, it was so nice to be only steps away from your room. After a long day of walking (and carrying/pushing a sleepy child) that convienent distance is worth it. I didn't even think of things like bad weather/storms/down pours... and being the closest building to the main building meant we weren't having to run through the rain!
We're big refillable mug fans and the proximity to the food court was huge for us. We could easily grab coffee and snacks in the morning while others were getting ready and it wasn't a timely ordeal.
Being so close to the main pool was great. It was nice to come back in the mid afternoon to kick back and swim. Being steps from the main pool/main building, we'd bring out mugs and towels and just relax. The main pool played music and pool games through out the day and it was nice being able to run up to the room if we needed something. All Star Music also plays pool side movies during the evening at the main pool.
To us it was worth it, cause while yes, we spent most of our time at the Parks, there is that time when we're at the resort and things like a preferred room do make things that much more convienent!