I only found this out after we've had several clients place tickets stating that audio out was not working. I can vouch they do have a 64bit version now. Well, four versions if you count the browser version.
They can focus all their resources into fixing any issues/bugs in THREE versions instead of SIX. So having ONE single install for Windows, ONE for MacOS and ONE for Linux solves a lot of potential headaches on both the user end and Zoom's support end. I don't know if you've spent a lot of time on Zoom and then a lot of time on Webex, but the difference in UI is like night and day. They complaints are generally minor and if there was real serious major major problems with Zoom, everyone would ditch the platform for something else, like Webex. For the millions (billions?) of users on Zoom in this last year, there is relatively little complaints. One of the things that has made Zoom so popular is it is like Apple made a video-platform. While a 64-bit version might run a little faster with fewer system resources, there are still lots of people out there with 32-bit machines and cannot run 32-bit versions. My limited knowledge suggests that perhaps it's not necessary or worth it to produce both 32- and 64-bit versions.
Good question, I look forward to hearing from someone who might know.