Cucumber isn't only a testing tool. Besides testing Cucumber features also take a role of documentation, a mechanism to collaborate with stakeholders and requirements storage (if you write them in declarative style).
You don't have to use Cucumber with Capybara. You can use selenium directly. But Capybara has the same high-level API for all supporting drivers. It's more high-level than Selenium's and allows to write tests a bit faster. You don't have to change code when you switch from one driver to another.
Tests built using test recording tools are generally much worse. Selenium IDE may produce valid programming code but it's not good-looking and thus quiet difficult to maintain.
