The proposed advantage of Type 45 lies partly in having a radar system different from Aegis. An opponent concentrating on countermeasures against the widely used American system would not necessarily have put the same effort into SAMPSON. That difference could make a British ship useful alongside American ships. Developing a separate system also spreads substantial development cost over a much smaller production run.
Notable Point · 23:58-25:16
How a different radar system could help an allied task group
The Type 45 example links radar diversity within an alliance to countermeasure planning and the cost of a smaller production run.