I took another look at the preview, and while I was a little hesitant about the noble education part, I think you are most aggravated by the hit point issue.
To me, it looks as if the Noble gets 1d4 hit points per level, only the book uses the option (from the DMG) of giving slightly below average hit points without rolling. On first level, they get full hit points (4 from 1d4), plus 4 hit points extra, maybe to make them a little more resilient. Truth be told, if wizards would get 8 hit points at first level (as well as rogues, bards, etc.), I wouldn't be too concerned.
Anyway, the hit points seem to follow a linear system (namely 2 hp per level). I'm not sure whether the book will have a line saying "If you want, you can roll hit points, where 2=1d4, 3=1d6, 4=1d8," and so forth). I'm not sure I need one.
For example, a noble 3 will have 12 hit points, a noble 16 will have 38. A wizard 3 will have 6-12 (average 9), a wizard 16 19-64 (avg 41). Frankly, I don't see your problem here.