I'm not sure if "bigger" means larger sensor area (and I also don't know of a sensor that is between MFT and APS-C) or more megapixels. It could have been something lost in the literal translation and leakers are talking about resolution and not...
Arguably the old way was better as you could cancel if you timed your moving of controls just right. So you could capture the images but cancel the stitching part.
Yes, 70mm - DJI hates that one simple trick.
1. General rule of physics - nothing is free. Stitching takes a LOT of CPU resources and drains the battery
2. You cannot take photos/videos while stitching is in progress.
Unfortunately from what I understand the drones that have built in stitching will stitch and there is no option to turn this off. Yes, waste of time, battery and SD card space for those who don't need it.
In the past the stitching could be...