The two biggest reasons would be
1) to turn an expense (for usage) into a revenue positive event (from other sales made by that firm)
2) because the price seemed cheap. For whatever reason. A nd most could be done in stock. A gain, cheaply.
If you can buy something cheap and have it add to the bottom line, and it integrates well, then it is worth buying. If it doesn't integrate well, it is not worth buying. They obviously think it integrates well.
That's the two reasons to do this deal.