That is a question which should be constsntly asked when it comes to tools and products in general.
It applies to bikes and is discussed here all the time.

To answer you-
- I do not think 2 pumps equals 'many'. Sure it is more than 1, but it is hardl 'many'.
- Having a separate ball pump means you don't have to remove the mini pump from your bike and potentially forget to put it back.
- A mini pump for normal bie tire filling before ridesas fast or convenient as a florr pump.