Hi,
Some TestStand users start the way you are thinking.
They build a UI which will support some type of scripting ( read from .csv) or something similar.
When the project grows they keep adding new features like DB,Report,process related cusomisations,Support for different instruments whose drivers are in different language,etc.
There is also a considerable amount spent in maintaining this framework.
He spends time building it ,testing it,maintaining it. ( costs )
If the person who built it leaves then its a big challenge to others to take over.
So person who is supposed to build ATE,build test sequence or its module softwares ends up devoting his time to developing a framework which is already available in market.
In short if your development is a one of thing then you can develop in C# but if you see a scope for development/maintaince in long term maybe you need to consider TestStand.
Ravi
If you have a one of development maybe you can develop uisng C#
