Well, it comes in handy in many other situations, too, especially when you can't get your grubby mitts to the display, but rather need your next turn, incoming caller, text or email read out loud to you, like during driving. TTS engines are also important for 3rd party apps which need to integrate speech synthesis for a more complete experience, like the numerous voice-controlled assistants that have invaded the Play Store.
Android's default speech synthesizer is decent, but not always present from the box, and if it's there, it sounds modeled after Stephen Hawking's first TTS machine, and not the sharpest tool in the shed when it comes to languages, hence manufacturers are often making their own combos - Samsung and LG each have their text-to-speech sets preloaded, for instance.
The trouble with those is that they are usually loaded with the area settings where the phone is supposed to go, or you have to go to third party app stores to get different language packages or high quality pronunciations, like with Samsung's own TTS engine. That's why we are rounding up some of the best text-to-speech engines available in the Play Store to show that you don't have to settle with the limited monotony that typically comes with your handset out of the box.