The answer is simple – your team wants to build more reliable software; more effectively.
One of the biggest issues facing any development team of more than one developer is ensuring that any changes being made do not break other parts of the software you are collaborating on. While this is often mitigated by developers working on separate parts of the system based on their area of expertise, in the golden age of object oriented, re-usable code the impact of any changes has become harder to track and test.
The initial benefit of a bare implementation of a basic CI system provides an automated approach to something that your developers are probably doing manually already. Every time a branch is merged back into your main branch (a future article will explore sensible approaches to branching and merging) CI kicks in; prepares a test environment and checks the main branch into it ready for testing – in itself an incredibly useful start.