I did not say it's not expressly forbidden. I believe it is forbidden for Christians as
@frederick has outlined - this is a later instruction, so it does not contradict the fact that Israelites could marry captured women. Nor is it incompatible with the idea of marrying captured women - if they converted during the 30-day courting period. And it's particularly important to follow in Western culture, while it was less of a concern in ancient Israel hence the lack of a prohibition in Torah.
In the Qur'an, this issue is grappled with because Islam is fundamentally militant and quite keen on the idea of capturing wives... Their policy is that a Muslim man can marry any Muslim, Christian or Jew, but not a pagan, and there is an expectation that if they marry a Christian or a Jew she will ultimately convert to Islam. I am not in any way promoting this theology as correct! But it is an interesting practical application of these basic principles. In other words, taking a historical cultural perspective, I take this to mean that a Muslim's wife must have a basic foundation of common religious belief to him (monotheism, patriarchy etc), and that is sufficient for starters, with the expectation that she will follow his headship ultimately. That is very similar to
@rockfox's statement that it is more important to find a submissive wife who will follow your leadership, than one who nominally claims to be Christian but is fundamentally worldly. Which shows it's a pragmatic, logical position that others have come to also - whether or not it agrees with scripture being a different matter, I just find the parallels interesting.