Alloy does not distinguish a manually generated post from one that is created by the Editor. It has no way to know to magically set the time to midnight. Each post is simply a markdown file.
There were a great many users who requested time based future publication, which is what brought on this new feature. It is implemented the way it is for several reasons, one of which includes filename formatting problems that would arise from inserting a time value in the file name itself.
To do so would not work now, or as a future feature. Setting the time in the file name itself would be unwieldy in standard either 12 or 24 hour formatting, as well as be an invalid filename. There could be a way around that but it would require using PHP formatted time values, which you’d have to build a converter for to use, so that is out as well.
The large majority of users wanted time based future posts. Likewise the vast majority of users use the Editor for their posts, so Alloy has pushed towards the Editor as the way of managing posts.