All of that is simply some form of heating up your food. You might be heating up your food in a different manner, but that's all it's doing. But sure, lets say microwave is a bad example and move on.
Computers is a much better example, though not a good one personally. I'm going into programming so that I can access the crazy stuff computers can do. Cars is another good example, and while I'm not trying to upgrade my car to do more stuff, I'm fully cognizant of what you can do with a car. I'm just not interested in learning those skills because all I want out of my car is a means to get from point A to point B.
But that's the thing, I'm interested in computers and put my effort there. I'm not interested in cars so I don't put any effort in there. I imagine most people are the same for their own interests and hobbies.
Magic though, doesn't follow that. Yes, it takes time and effort to learn and use, but by the rules of magic in El Goonish Shrive, you will get spells that are a reflection of yourself, and thus are almost always something you are interested in. (Barring awakening improperly). If I had access to it? You can damn well bet I'd be focusing on improving it as much as possible. Afterall, whatever I get will likely help me with what I want to do in life or my daily life because it's a reflection of me.
And we've seen how easy it is to improve your magic. It simply just casting as many spells as you can til you run out of magic. Nanase was able to practice her magic while going through her daily school life. Alright, she had subtle enough spells to do so with, but it wouldn't be much harder for say, Ellen to zap herself repeatedly, or for Susan to put a pencil in her box and repeatedly summon it. It is substantially harder to get good at programming, or to rebuild a souped up engine of a car.