Do I need to have iCloud backup

You can use either iCloud for backups, or iTunes (or both). But yes, if your data is important to you and you do not wish to lose it, then backups are necessary, not optional. That goes for every single computing device you own. If the data matters to you, back it up.

Need to? No, but it is usually a very good idea. iPhones and iPads are portable devices that can be easily lost, stolen, or damaged. If you have any data that you value on the device and it is not backed up to a computer via iTunes or otherwise synced somewhere off of the device itself, I would highly recommend that you do something that keeps a copy of the data safe.

I concur with FoxFifth on if backups should be done.

There is the old IT saying about backups which goes something like this; lose of data is a certainty, the only question is when will the lose occur.