Air Asia is a low cost airline.
Yes they are basic - but the price is basic too.
I love to fly with some space around me on a longer flight, happy to sit in coach for short intra asia flights up to 3 hours.
D7 in premium is awesome for the longer flights - I recently paid $315 for KLIA2 to SYD (in premium) - I will not be complaining about anything on that segment