There was a time up until a decade ago when having a mobile app was a luxury and the app store was still a subject of novelty. Over the years, possessing an app is no longer a trump card; it is no longer a necessity.
Ergo, having an app just for the sake of it would pay no dividends, in fact, the construction, the maintenance and the fine-tuning alone will create a big hole in your pockets. Hence, this decision is a critical one and demands your attention right from the get go.
However, its not all gloomy in the app world as it might just give you a chance to expand your customer base substantially whilst bringing your products and services to a more targeted gentry of consumers. Its up to you to reap the benefits after all.