Regardless of whether you like his videos, or not. I think he is correct about the margins that companies make with their hop-up products.
There are so many reasons why we buy hop ups, for Tamiya owners, I guess most buy them mostly for the bling. I own a lot of different brands other than Tamiya over the years, from what I understood, you almost certainly would not buy a Tamiya if you are into racings (not the Tamiya cups I am afraid), not even the TRF series. There are always better fully breed racers such as Yokomo, Losi/TLR, Associated, or X-ray these days. My very first Tamiya was the Boomerang, and the only upgrade? Bearings. It didn't last long, because in those days, there was no fail safe on the AM radio with the mechanical speed controller. I bought a TA02 with my summer part-time job money, and I only upgraded parts when they broke, still, I ended up with the original FRP chassis, full bearings, one way gears/hardened shaft, universal shafts and ball diffs, anti roll bar and some metal dampers. I reckoned that I could have bought the Yokomo YR-4M instead with all those money. But it is an addiction after all, and there wasn't any Tamiya blue in those days.
Zooming back to the present day, Tamiya leads the way in their marketing in the RC world, they also introduce new ways of making even more money by organising Tamiya only races around the world. There are so many restrictions such as Tamiya only hop-ups. I was told that in Japan, they are now introducing budget cap for beginner racings such as USD100 worth of hop-ups (Tamiya list prices), probably to answer some of their critics. In my opinion, this is the way to go, to have a more level playing field.
P.S. About the issue of adding more weights with metal parts.... I think those aluminium parts can indeed strengthen the chassis and remove some of the sloppiness and play. Adding weight may not be a bad idea, it depends on where on the chassis, plus there are minimum weight for some races where people need to add more weight anyway.