I think knowing VB and/or C# is always a plus. But I am probably at 1 (out of 10) in this, and I have survived. It also depends on what project or where u land job on. These Days after 2005, u hardly see any VB or C# scripts in SSIS as a script components. I have used few, but then I have always able to find code online whatever I need.
But if you want to talk about or even use in SQL then Learn it and more imporatantly in CLR functions. In work place, u hardly see any place where you will use all of these at one place. In work place it is very specific what you will use on a regular basis.
From interview perpective knowing them and able to talk about them is always a plua and will seperate you from others. So my suggestion- Know the high level stuff, know what they are, how it can be used, and when time comes to actually use it, you k now where to look.
hope that helps..