Baptiste: I understand that for you it is not a problem, but think about it from a beginner's viewpoint, and from a UX perspective.
Beginner: Many people will see "Computers" and think: Yes, I want a Computer program (vs smart phone or web site), so they click "Computer". (The Amiga is a computer, so the type of computer may not even occur to them.) Then, when they decide to add the #manifest: "amiga" tag, they'll be confused when AOZ does not use the Amiga configuration, even though they told it explicitly to do so.
UX: The eyes normally tend to focus on the upper left portion of the display.
The upper left (and therefore the most prominent) selection on the New dialog box is "Computers". They may not even look beyond that selection if it applies (which it does).
NOTE: The New dialog box even explicitly states that you will be able to change the template at any time!
For future versions of AOZ, IMO, we should allow the users to change the template at any time, (as well as on-the-fly), so a single program could optimize itself for multiple configurations either automatically or programmatically. Think about it. This would be a great way to set up user preferences for an AOZ application - by using a programmatically selectable manifest! (We could set display resolutions, columns, etc.)
Of course, they should also be able to "tweak" the settings in custom manifests. This would be a practical application of the manifest editor, a tool which Francois had previously suggested creating.