You're not alone. Unfortunately, that "feature" still exists in Excel 2013.
It's like having the cruise control turned on by default when you first start your car...you want to go 65, right?
We have part numbers that get "corrected" all the time and since a lot of people within the company use Excel, it's often unnoticed and emailed out internally and to customers. And then, if you don't notice that there was previous conversion and you drop
it in your own spreadsheet, you end up with another mess and the only way to get back is to have the original person reprocess their data because once it's in there, it stays there.
I was just looking at some data today and discovered that my bar-code numbers got automatically converted to what looks like latitude & longitude.
What's crazy "funny" is that I never EVER want numbers converted to dates (even if people mean to enter dates); I simply want exactly what people enter. If I need, I can convert stuff to dates.
Simply put, Microsoft needs to make the default the least intrusive...no auto formatting. When needed, conversions added from the options menu. Unfortunately, I suspect they don't have the employees available to update programs like they once had.