The distinction between hymns and praise songs is a modern distinction, that has nothing to do with the original use of the term "hymn".

The term "hymn" as used in the bible, simply refers to a "song of praise". But today, hymns usually refer to a certain group of old church songs, irrespective of weather they actually praise God or not. For instance, all the congregational songs of Fanny Crosby and Isaac Watts are considered hymns today, even though some of them aren't songs of praise. Meanwhile, the entire genre of what we now call "praise songs" is typically thrown out of the hymn category, even though many of them are true songs of praise (and therefore hymns by the more traditional use of the word).

The apostle Paul in the bible, refers to three types of song to be sung by congregations, hymns (songs of praise), psalms, and spiritual songs. There is however, a fair bit of overlap between these three categories and some songs can fit into all three at once. Some of the Psalms are very much hymns (songs of praise), but not all of them.

One should not totally dismiss the entire repertoire of modern "praise music" as shallow or "Jesus Is My Boyfriend" (a term that I disagree with). Neither should one totally dismiss the older congregational songs (hymn or otherwise). Their are spiritual gems and dross from both the modern and old. Sound theology is important, but I disagree with the notion that all or even most of modern "praise music" is promoting bad theology (less theological content would probably be more accurate). I also don't agree with throwing out all references to the blood of Christ or to his sacrifice (which some church hymn books are guilty of). Christianity without the cross of Christ is neither true Christianity or sound doctrine.

Quite often today's "praise music" is criticized for being emotional. But is it necessarily more emotional than the way the Israelites sung their songs in the bible? Just check out the Psalms for evidence, with references to dancing and shouting for joy (considered irreverent by some church traditions). I have heard some old time African American hymn singing, that is just as emotional in expression (often coming out of a very genuine faith in Christ). I'm not saying, we should throw our brains out, but I don't believe much of this criticism is coming out of anything biblically valid. A lot of it comes across as pharisitical to me.

There is much in the modern "praise" genre that I find distasteful. The strong lack of good poetry or well written artistic lyrics is common place (I often prefer hymns for the lyrics). But simple songs and repeated lyrics like chanting "holy, holy, holy" do have their place, and are often a genuine and biblically sound expression of faith. Yes, even if it's not to my musical taste (There is some praise music to my taste, though a lot of it sounds like drivel to me).

As for modern praise song borrowing from popular music, there is nothing new about this. The old gospel song or gospel hymn style of Fanny Crosby, Ira Sankey and others, was very similar and sometimes no different than the old parlor ballads (which was mostly a secular form of popular music, especially common in the 19th Century). The gospel song "In The Garden" is essentially just a sacred parlor ballad, sharing the same musical and lyrical form as the secular. It has very sentimental lyrics (common to the parlor songs) and very little theological content.

One might think that the "classical hymns" (based on the melodies or style of European classical composers) is free from any kind of popular music influence. But if one actually digs into the roots of classical music (as author Peter Van Merwe did in his book "Roots Of The Classical), one finds that it was partially based on older forms of European popular music. To put it simply, European classical music would not exist without the contribution of popular music, and thus the "classical hymns" are "tainted" by pop music.

That's my 2 cents.