Even though I agree with you on the most parts, I think it's worth noting that it is extremely difficult to return items on Steam (if at all possible). Also, keep in mind the price differences Valve places upon customers. A game can cost $35 in the US and costs 35EUR in the EU. I have also personally purchased a game online which required activation on Steam. When trying that, Steam told me I was not allowed to own/use that game where I live and that I should return it. Steam in general refuses to sell me any games that aren't watered down to the lowest "violence" levels. Even though I can buy the original versions right at the store.
Also, "high speed" is kind of a debatable term in this context. I guess 2MB/s is a high speed (I hardly ever get beyond that). But downloading a game from my library still takes longer than installing it from a disc. And the connection issues are even worse for the dedicated servers I run. Installing/updating server installations have always suffered from low speeds for me. This can be very frustrating at times.
I still agree that Steam is most likely the best platform of it's kind around and I appreciate a lot of the benefits compared to retail games. Yet the above mentioned experiences leave at least a bitter aftertaste.