My understanding is that forecasting is highly complex and skilled in the real world. It does involve complex maths and is incredibly difficult to do well, which is why it is done so badly in a lot of companies.
Regarding food preparation, it's made clear in later books that it isn't magicked up out of nothing, like in Star Trek; a person makes it, either a family member, an employee or a slave (a contentious topic which doesn't seem to be covered in this thread, but I may well have missed something) and when it is all ready it is then transported to the table by magic. Magic in food preparation is mostly limited to simple tasks like chopping and stirring, at the level of kitchen gadgets.
Broom velocity is unlikely ever to reach light speed because most of the improvements are likely to be superficial, marketing BS like in the real world, and the pace of change in the wizarding world can be justified as much slower than in the real world simply because the community is so much smaller. Fewer people can be freed up to do research, and the pool from which to draw great new ideas is also correspondingly small. This also partly explains why social change is slower too, though I expect snobbery would play its part; why change, when they are already far superior to the Muggles?
I love the stories, and have been collecting the illustrated editions as they come out - they are great! When they were still being written I would re-read all the previous volumes, in order, whilst waiting for the next one to be published, just to be sure I was up to date with what had been happening and was fully prepped for the new one. If I had dedicated the same amount of attention to my school work, I would have done much better in my exams! But still I don't remember everything, and every time I read the newest illustrated volume I am surprised by something 'new' - sometimes I'm even driven to go and check my original copies to make sure it isn't a modern addition to the text! I am therefore not an expert, just a happy consumer, and as such I don't care to critique it logically. The suspension of disbelief is as important in reading fiction as it is in enjoying a movie, and all reductive analysis should be done just for fun. Otherwise you are crediting the books with far more significance than they actually have unless, of course, it is some sort of parable and is intended that way, such as Animal Farm. Which I have never read. The first few pages put me right off!
