I personally think Epic Games failed in portraying Tai as a mystic character . as far as I know religious guys never commit suicide . also Tai himself said : everything happens for a reason , if he believed in what he said then why did he choose the easiest way ?!!!!!
Also I personally did not miss him when he killed himself , in fact I felt sorry for Marcus Fenix . have you seen his face during the suicide sequence? it was the only time that Marcus was so shocked during the GOW1 & GOW2 !