I can understand the impulse among the mainline denominations. It probably makes them self-conscious to be so graphically reminded every Sunday of their own denominations' journies.
It should be conceded that St. Augustine and John Calvin considered the descent into hell metaphorical and that differences exist between the Roman Catholic, Eastern Orthodox, Lutheran and Calvinist understandings of its purpose. Moreover, "hades" only indirectly means "hell" in Greek; its primary meaning is merely a reference to the abode of the dead. John Piper, who is hardly a radical, is among those who wants to remove the phrase from the creed despite its antiquity, claiming that the concept is not biblical.
The Bible itself disagrees, however, and in context I think the meaning of "hades" in this connection is rather clear:
For Christ also suffered once for sins, the righteous for the unrighteous, so that he might bring us to God, being put to death in the flesh but made alive in the spirit, in which he went and proclaimed to the spirits in prison, because they formerly did not obey, when God’s patience waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight persons, were brought safely through water. Baptism, which corresponds to this, unow saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ, who has gone into heaven and is at the right hand of God, with angels, authorities, and powers having been subjected to him. (I Peter 3:18-22 ESV)Whether the descent was for the purpose of liberating the spirits of the patriarchs, as the Roman church teaches (a bit of a stretch, I think, if one relies on the text) or to proclaim His victory over Satan and hell, as Luther taught, I don't think it's possible for anybody who recognizes the canonicity of 1 Peter to deny that the phrase "he descended into hell" does not merely date from the earliest era of Christian liturgy, but is absolutely biblical.