There are a couple of things going on here and I think it is easier to split them out.
Probably the biggest advantage to a mid-drive over a hub drive is that you will have superior hill-climbing ability. A smaller but still noticeable advantage for many riders is that you can get slightly more range, sometimes dramatically so if the route you are riding is at all hilly.
Mid-drive bikes have been under furious evolution the last several years. Upgraded component sets (which can better handle the higher torque from a motor) and frame designs specific to mid-drives have greatly improved the durability and reliability of mid-drives. So one reason there are lots of discounted mid-drive e-bikes is because they are like last year's iPhone.
Finally, as I've said multiple times, motor wattage figures are Not To Be Trusted. The manufacturers are all lying, and they are lying for different reasons and in different directions so it is impossible to make meaningful comparisons based only on wattage.
Both hub-drive and mid-drive bikes are useful. If I lived in Florida or Nebraska it would be a no-brainer to ride a hub drive. But I live in the mountains so I want a mid-drive.