If we are exposed to repetitive tones for a length of time our brain will tend to filter it out of our focus, for example an air conditioner or the sound of cars passing outside.

The same effect can happen with music: if it’s too clinical and repetitive it may not keep our ears intrigued. 

This doesn’t mean you have to constantly keep your music evolving however you may want try some subtle movement.

One of my favourite examples of this is programming hi hats: by introducing a random sample and hold LFO on sample start, volume and/or pitch by a small percentage (2-5% for example) you can get a live feel as opposed to something robotic.

The same goes for synths: some really subtle detune of the oscillators or filter positions can go a long way to breathe some life into your music.