FatimaH, many a times our traditions, rituals & socio-religious customs are so forceful & mind-masking that anything abysmal is perceived as 'normal' which may not be the case actually if the same is comprehended in full freedom.
Fact is, child marriage is a bad thing in general, there may be many success stories out of it but they’re just exceptional cases.
Good thing is, a sea change in people’s attitude against child marriage.