To my knowledge, it's only possible to have either 32-bit or 64-bit per Microsoft Store listing. That means that I'd need to add another listing for the 64-bit version, which I currently don't plan to do.
Instead, I want to switch to 64-bit at some point in the future and let those who rely on 32-bit fall back to the standalone version.
And to add a new supported language, I need to add a completely filled in store page listing for each additional language, which seems to me like the most boring work for 40+ supported languages. It's on my list, but I wasn't bored enough yet.