So, basically you just use the card instead of cash in pocket? That can be done with a debit card as well, as you seem to basically already have the money.
Ok, I can understand 30 or 60 day, sometimes even 90 days (Don´t know if have in Thailand) without interest, can be fun. Not really useful as you pay with money that you probably already had at the time of purchase.
It might also be like you have been working in Thailand or still working, which means you did not need to lock up any money to get the credit card. In that case, it´s of course more reason to have it.
Myself, is a cash guy. Not that I walk around with a lot of money. I have a few debit cards that I use, but always pay all in full. No loans or credits for over 30 years.