Commonality is one good reason. Another is cost. Designing new classes of warships is a long, expensive process. By buying a class from someone else, even modified to incorporate your own indigenous systems, you save both time and money since someone else has already done the design work and testing on the new hull. Also, the sprucan in perticular was a flexible design. Look at the differences between the USS Spruance and the USS Port Royal (the last Ticonderoga class cruiser.) The two share a common hull design, but have vast differences in role, sensors, weapons, etc.
I agree on that. but that does not explain why they chose USN designs instead of the british and french ones, as done IRL most of the time when the dutch did not design them themselves.