Ironically single-origin coffees (or chocolates, etc.) are vastly more interesting to most people because they are so unique and can change unpredictably. There are ones with tasting notes resembling oranges, tomatoes, etc.
True. But that unpredictable change in tasting notes is the enemy of commercial packaged coffee: your box of illy, carte noir, maxwell house, nescafe, nespresso MUST taste the same every time, and MUST have a stable cost of raw material (apart from baseline coffee prices fluctuations). The same happens for chocolate and tea (lipton's and twining's teabags can be a mix of 20-30 tea varieties that change continuously)
Just to add to gpresot's comment, every large brand has this issue. McDonald's products need to taste exactly the same around the world and most of their brand's value lies in the ability to create a stable, unchanging product that is still attractive to their market segments.
Buying single-origin, and accepting the instability that comes with it, by necessity requires microbranding.
In my experience, McDonald's burgers taste noticeably different in the US and Canada. So I think it's a per-country thing (especially when, e.g. Canadian McDonald's only uses Canadian beef).
Only good single origin is better, one of the main reason for blending origins is to hide flaws. So only a small selection of coffee/chocolate etc will taste good on its own.
