Malaysia standard, all electrical appliances with accessible metal parts should be earthed. Most of china made light fitting doesn't come with earth connection, but u still need to at least, touch the earth cable to the unpainted part of the fitting.

There's no harm if you do not install the earth wire, the lights still do what it does, but there's the danger to user. If the light fitting is energized, either due to pest or human error, it won't be detected by the ELCB. Anyone touching the light will eventually be electricuted. To re-do or not, its up to u.