Two words. Less money. If they were to acquire it you pay a market value as a whole. Licensing provides use of product at a current lower cost when compared to owning or purchasing.
As a startup would you want to pay 30 million for something if you don't know what to do with it or if you can market it or sell. Nope! You license it to see what can be similar to a demo or lease and decide if you like and can use. Der