Disrespect? Disrespect would be releasing the game without any new content.
I understand where you are coming from, and I see arguments like yours constantly (“I bought my super BMW/Mercedes and the new model has 50 more HP! How dare they!”). Every manufacturer has to differentiate their product from previous iterations, else no one will buy it. Also, it is much more likely that a person will be a repeat buyer than a brand new customer for any given product, as it is a much tougher sell to have someone buy something without any previous experience with the product.
All in all, I’m glad that we have the opportunity to buy 21 new sculpts (I don’t think the 16 and the 5 new sculpts will overlap). Whether we take advantage of that opportunity is up to us. If WotC wanted to release a super 1939 game with 200 unique new sculpts and powers, and charge $2000, I would still be happy, even though I most probably would not buy the product. Opportunities can never be a bad thing, as long as no one forces you to buy the product.