Good idea! Stealing this for my next ideation :)
...all jokes aside, while I know most of you would rather see new content and it has been 2 hard modes back to back I don't see anything inherently wrong with them and as the blog states, the intention isn't to give you this stuff instead of new content.
Both Phosani and ToB Modes were ideation pitches aimed to address the lack of PvM updates in the short-term that were relatively cheap to develop and were also mostly finished!