Interracial marriage and immigration have a lot in common morally.
Immigration that is wise, just and limited is morally neutral, or positive. Unwise, unjust, and unlimited immigration bad for all involved.
The same parameters apply to interracial marriage.
The deleterious and degenerate forms of both are being used against the ethnic, and religious West. Not all attacks work against everyone, so all kinds of attacks are used. Some are involuntary like illegal immigration (and the resulting gang rape); some are voluntary, like abandoning your race, and culture and such in order to be inclusive or whatever. No means will go unused.
The morality of the actual begetting of the interracial children comes down to their own individual cases. Two smart, or beautiful people aren't guaranteed to have perfect children, or any children at all. It may be more likely that they will be good enough, but that doesn't help the one retarded child they have, or the one miscarriage. It may be more likely that certain combinations are worse than average, but that is not for society to police. We don't police white marriages that have more miscarriages than average, like some kind of three strikes rule.
When immigration is not out of all control, the admittance of immigrants is based on their individual cases. The same applies to the marriages.