I also liked that this software allowed you to move the mouse around to create entropy, I wonder why Bitcoin wallet generation does not include this feature.
Nowadays it's mostly not recommended to use any kind of user-action-derived data for entropy generation, since humans are incredibly bad at creating true randomness, even when trying their best to do 'random' things such as mouse movements or even selecting a random sequence of zeroes and ones.
There is a number of scientific publications on this too, as mentioned in this StackExchange answer:
https://crypto.stackexchange.com/a/87982