E.g. also the JMSDF had the radars separated on the Akizuki class but they are combined on the bridge on the following Asahi class.
The risk to lose the radars to a single hit is for sure higher in case of a Arleigh Burke than in case of a Ticonderoga (which have no SPS-49 anymore!), but if one half of the SPY-1 radars of a Ticonderoga is hit, the ship loses half the coverage: only 180°, no longer 360°. That means the remaining half is also close to useless - and that makes it probably not worth to separate the antenna with the associated extra coasts and space issues.