It is not Why ERP? It is when ERP? ERP is the cost of being in business.
Many enterprises thinks, that we are small and hence we do not need an ERP system. This is the point that individuals start keeping the data close to them and they do not share. If one person does in the organsiation, the others will also follow them. It does affect the organisation, but it will not be realised when the organisation is small.
But as they grow, the same attitude continues and the conflict between departments are magnified, hence seen very glaringly. Now the organisation pays a heavy price for the damages.
Also many a times, the 1st generation entrepreneurs, may tell their successors, that I have been running this company with our ERP systems for the past 25 years. They need to understand that the new age entrepreneurs are more tech savvy and it is obviously the smart way of working. Moreover, many of the new age professionals many not choose the organsiations, who are still on manual systems, even if the organisation are willing to provide them the right compensation. In this way, the organisation which does not have right ERP system, will not be in a position attract the right talent too.
ERP is not costly, but not having ERP will be costly.