Money. We all knew that, I assume, irrespective of whatever nonsense they spin about using the TV show to adapt more of the content from the books. Potter was a smash-hit, and big executives will therefore wheel it out until the wheels fall off - just like with Star Wars (1977), Star Trek (1966), Lord of the Rings (2001), and more. As such, they keep making cash of the goodwill of people who enjoyed the last adaptation, and we keep getting suckered into watching identical stories with hardly any changes because people just aren't willing to risk a new IP.
the new Harry Potter reboot is just the newest in a factory procession of soulless, thoughtless and mindless readaptations of existing content
Whatever way you slice it, the new Harry Potter reboot is just the newest in a factory procession of soulless, thoughtless and mindless readaptations of existing content. To some degree, I do understand people wanting more of what they love, to get to spend more time with characters who they have grown up admiring and following the adventures of, but the fact remains that this TV series is unlikely to bring anything new or innovative to these stories.
As I see it, the time has come to let the Boy-Who-Lived finally die, and let the space he occupied in many people's childhood remain as a nice memory. I'm sure many will disagree and go on to watch it regardless, but for the foreseeable future, I'm done with flogging dead horses, sinking ships, and cash grab reboots.