There are a few reasons you’d want to take them out.
- It’s pointless. They add no value.
- It’s confusing. What is being used from that namespace?
- If you don’t, then you’ll gradually accumulate pointless
usingstatements as your code changes over time.
- Static analysis is slower.
- Code compilation is slower.
On the other hand, there aren’t many reasons to leave them in. I suppose you save yourself the effort of having to delete them. But if you’re that lazy, you’ve got bigger problems!