Just curious, why the change and are there any plans to compile future releases as 64-bit again?
Why the change: because it is twice as fast to compile just 32-bit, a 32-bit-only executable is smaller and faster to download, and there is no advantage to running 64-bit (bitcoin doesn't need more than 4 gigabytes of memory, there are no performance-critical routines that would be faster running 64-bit, etc).
If there's a good reason to compile 64-bit, or if we ever drop support for 32-bit Macs then a 64-bit version would make sense.