There is already VisualBasic for Applications which is just similar to Python, only with begin/end-blocks instead of indentation. And with a little fiddling you can also use JScript/WSH to remote-control some parts of Excel, as well as all the .Net languages.
The libraries in VisualBasic (before .net) do suck. But syntactically, Python and Basic are very close. I hate both very much, because all the nice features that make programming fun are lacking. Both feel very much like using a childs' toy instead of proper tools.
I code in VBA constantly as a Finance Manager. I also spend a lot of time learning Python and used it throughout a CS Degree. VBA and Python are not alike at all IMO.
You are right that you can use something like C# to manipulate Excel files, but there isn't a ton of tutorials on it, which makes it difficult and prohibitive to learn.