I agree, ATNotts, that the cabin storage of the 146 is small (largely due to the high wing deisgn) but it was designed in the early 1980s and production started in 1983. Of course, there were later developments but the basic design is naturally unchanged.
My guess is that, 30 years ago, they guessed that people would be having small carry on bags. Laptop computers simply did not exist, leave alone the other issues of connections and so on that we are discussing here.