CSV is convenient. The likes of Excel, Google Docs, spreadsheet export functions, and reporting applications all support CSV in some capacity. CSV works well with large data sets and the major perk is that it can easily be converted to other formats such as XML or JSON.
This is where the hard part starts: how do you easily convert CSV data for your app, MVP, or SaaS? For JavaScript-based applications, there are a plethora of free CSV parsers available. While these libraries are great, open-source is known to pose a security risk such as relaxed integration oversight and potentially poor and integrated practices.