You don't appear to realise how few people are like you. There are 12 confirmed kills of DG. That's it. That's not even 100 players. No company that wants to stay in business is going to create content that only 100 people ever see (ie everything past DG).
The fight is still far beyond the capabilities of at least 95% of the playerbase. It is hard by any reasonable definition of the word. If you don't find it hard, then you're just very unusual.
Really??? How many cleared Sunwell and Naxx 40 in comparison to the population? Last I check those were the 2 largest period of growth for Blizzard. And now that everyone can see the content, their population is steadily declining. History proves your theory wrong