Regarding old hymns:
Those hymns are a gift given to us by our spiritual forefathers. Yes, there are weak hymns that get replaced by stronger ones. Yes, there are some that are better suited to your theological or denominational position than others. But to simply throw out all hymns is to say that these gifts from those who have gone before us are worthless.
And for modern worship songs:
If hymns communicate God’s truth, modern worship songs help us apply that truth. They both have a role to play in worship and help us grow as disciples of Jesus. There’s a place for both of them in worship.
Great post on the need for balance and inclusiveness in our worship sets.