Possible counter point: while the unit-tester is busy writing perfect software. I'll be lazy... and perhaps I'll beat them to market and will use the resulting money to perfect the software.
I actually thought the same way you do until just recently. Once you get into the flow of writing unit tests, you'd be surprised how little time it takes, and how effective TDD can be. It helps me stay focused, and structure programs better. I can't say if it actually has slowed my development time at all, when you take into account fixing bugs found in functional testing.