Why should you install a custom ROM
A custom ROM interferes with your device’s operating system and replaces it with a new version which is better in its features and functions. Custom ROM gets your device to the latest Android version. If you have not updated your phone, then you can install a custom ROM for accessing the latest Android version.You can replace manufacturer skin with a stock version of Android by installing a custom ROM. If your device already has a stock ROM, then you don’t have to go for this.
Custom ROM installs skin which customizes entire looks of your Android operating system. Custom ROMs offer many other features other than these.