Harbeths are built according to the principles laid down by Harwood and the other engineers involved in the development when he worked for the BBC. Just about all LS3/5a et al follow these principles, including the sompanies mentioned in the Stereophile review. If you understand that, you'll understand why they look as they do inside. There's nothing cheap about them, the money goes into the development of the cabinet, drivers and crossover.
Magico use an entirely different approach, and presumably given their massive prices, obviously expect their owners to look inside and see bling. Harbeth, and Spendor, and Stirling expect their owners to listen. That, by the way, is the case for most speaker manufacturers irrespective of price, and, were you to open their speakers up, you'd see something as plain as the Harbeths appear to be.
By the way, I have owned Harbeth speakers, the small ones, but sold them as they couldn't compare with my SFs.