Why not use a text file in a tab-separated column format?

for some simple applications, do exactly that!!!

but here are some reasons why a file stinks:

• you need to read the file
• you need to parse the file
• you need to deal with the column separator occuring within a column
• you need to update the file
• you need to write the file
• you need to protect the file from tampering
• you need to protect the file from simultaneous updates
• you need to enforce column constraints
• you need to search the file
• you need to perform complicated searches on the file
• you need to index the file on multiple columns for fast access
• you need to provide functions for all kinds of column manipulations
• you need to sync the file across multiple slave or backup servers
• you need to enable queries involving an unlimited number of such files, mixing arbitrary column types
• you need to incorporate multiple man-centuries of high brain power in your file-access design for optimal performance
• you need to enable access to the file contents from multiple languages and applications, perhaps remotely
• many more reasons...

all these details are managed beautifully for you when using a good database engine!