Because of their nature, hymns fit well with a piano and/or organ. The reality is that most folks don't have an organ in their home. Some do have pianos. As in all church families, the music playing is limited to those who have the skill to play the instruments. If someone can play the piano, this makes hymn singing much easier.
Small groups of Christians have, by definition, a limited pool of musical resources upon which to draw. It may be that no one has any musical skill (for example, me).
Of course, no instruments are required for singing any song of any type. Therefore, the possibility of hymn singing should not be discounted out of hand in simple churches. It can be done a cappella.
My encouragement to all churches, simple or not, is to strive for a variety of song types. This responsibility falls on all the people. One person should not be asked/expected to play all the music and select all the songs at every gathering. Frankly, it's not fair to that person to ask them to do that much.
Hymns often require teaching before singing. They are not generally as easy to sing as are most modern choruses. At first, it may seem like work and feel plodding. However, the reward is great.
If you have grown up in relatively large churches, you may have certain expectations as far as hymn singing is concerned. The performance-aspect of singing hymns in the home may at first seem lacking. However, the community side of hymn singing, at least in my opinion, more than makes up for this. I love to watch people's faces up close when they sing deep theology. I take joy in viewing others take joy in Christ in song.
Hymns require some effort. Regardless of how you gather, the effort will be worth it. Select good hymns, sing them repeatedly until they feel natural, and enjoy.