Churches are genuinely ideal for adaptive reuse compared to most other historic buildings, and it goes way beyond just the dramatic ceilings. The structural bones are almost always excellent - thick masonry walls that stay cool and regulate humidity naturally, which modern HVAC systems struggle to match. The open floor plan you mentioned is huge, because it was designed to seat hundreds of people without internal walls, so developers get flexible blank canvas space without the nightmare of removing load-bearing columns. Plus, the mechanical and electrical systems are usually already surprisingly robust since churches needed to handle large gatherings, and many have already been retrofitted over the decades.
There's also a practical money angle. Churches often sit on valuable land in established neighborhoods - they weren't built in the middle of nowhere. Property tax exemptions disappear once they're converted to residential or commercial use, which pushes prices up, but the building itself is so structurally sound that renovation costs are often lower than demolishing and rebuilding. You're not dealing with hidden rot or foundation problems like you might get with a neglected warehouse or factory. The stone and brick construction also appeals to people emotionally in a way that an old office building doesn't, even if the latter might have equally good bones. People want those vaulted ceilings and architectural character for their lofts or event venues - it's just more marketable.