Most likely the main reason they want to do weekly episodes is to avoid a lot of people signing up then dropping the service after 1 month and bingeing the entire show in a day or two. This way they're more likely to last at least 2 to 3 months, and during that time may decide the service is worth keeping as they find other things to watch and enjoy over that time period. If The Mando and The Clone Wars dropped at the same time in November, and with all episodes available at the same time, I'm sure many would binge watch them all and pay for just a single month of Disney+. Disney wants to own our *****, not be a rental service.
Once it's released, I'm pretty sure this (and all Disney+ exclusive shows such as the Marvel stuff) will stay on their streaming service indefinitely. Doesn't make sense to remove it at all. It's their property. It'll never be shown anywhere else. And, depending on popularity, may never even see a home video release. Most Netflix shows never make it to BluRay either. So this will also force those who prefer to own to actually have to sign up for their streaming service as well.
I hope they at least release The Clone Wars on Blu, as it would really suck owning the initial 6 seasons (along with the entire run of Rebels) but not being able to own the final and last season as it's exclusive to Disney+. The Mando would have to be amazing for me to want to own it.