I think it is a matter of culture, rather than religion. My dad is of Northern European ancestry and mom is Armenian. I grew up balancing the two cultures and one thing that was very different was the degree to which emotion was allowed to be shown. On dad's side, everyone was very reserved, no matter what, even during funerals. Wailing and carrying on never happened. On mom's side, emotion was much more freely displayed. Wailing and carrying on happened quite a bit, and not just at funerals.
A couple of years ago, I attended a funeral for a Lebanese man who was Byzantine Catholic. He was in his thirties when he died, and his mother was yelling, crying and carrying on during the funeral. At one point she went up to the casket, threw herself on her son's body and, sobbing, began kissing his face and stroking his hair. It was very sad. I can't blame her--your child is the one person you should never outlive.
I know that as Christians we are supposed to be happy for the deceased, as the day of their death is really their birthday into heaven. However, it is easier said than done. There is still the void left when someone you loved and spoke to daily is suddenly gone. Perhaps it is selfish to grieve, but the grief is real and I think that God understands that. Remember that our Lord wept at Lazarus' funeral.
My mom always says, and I agree with her, that the Armenian way of mourning is the most healthy. For forty days after the death, the family fasts and is allowed to give full vent to their grief. It is understood that they are supposed to do this and there is no shame in it. On the fortieth day, there is a requiem and a meal at which the fast is broken. It is understood that at this point the family is expected to move on with their lives while fondly remembering the departed one. The more reserved, keep-your-emotions-to-yourself way of handling grief is, in my opinion, less healthy.