Hello, ShinehahGnolaum.
I understand you want to know the benefits of using iMessage. I may be able to help you with this. Check out these two articles:
About iMessage and SMS/MMS

iMessages are texts, photos, or videos that you send to iOS devices and Macs over Wi-Fi or cellular-data networks. These messages are always encrypted and appear in blue text bubbles. To turn iMessage on or off, go to Settings > Messages.

If you aren’t using iMessage, you can use SMS/MMS. These messages are texts and photos that you send to other cell phones or iOS devices. SMS/MMS messages aren't encrypted and appear in green text bubbles on your device.
Learn how to use Messages
I'd like to mention is that iMessages are always encrypted. Also, iMessages can be sent to another iOS device with iMessage by email address (Apple ID) or phone number where SMS is through the carrier and by phone number only.
Let me know if this helps.
Thank you for using Apple Support Communities.
Cheers!