On the jasmine team, it seemed to us that most people wanted to run their tests headless, so with 2.0 we made that the default. Running the tests in selenium also made the jasmine gem have a number of dependencies that potentially made it harder to install.
But we also see the value in running jasmine tests in multiple (real) browsers as well. To this end, we extracted the selenium code, including saucelabs integration, to it's own gem. Jasmine core actually uses this gem to runs it's own tests across multiple browsers.