I was enough of a geek that I loved the Meg's mom used a bunsen burner to cook, loved the explanation of the tesseract, fond Aunt Beast to be wonderful, and could relate to how "normal" kids treated geeks, particularly geeky girls. Back in the 1970s, mansplaining was much more common, so I wasn't surprised by it. I do agree with you that the dialog leaves something to be desired.

However, I didn't find Calvin's statement about how beautiful Meg's mom was out of line coming from a boy his age who was probably trying to cheer Meg up - given his age and the time period, this was probably the best he could do. I can see how a modern person would not like this book, but when I was 8, I enjoyed it. Would I enjoy it today? Maybe not, but if nothing else it taught me about tesseracts, which I still find very cool.