Hi Goustan,
The original post may be a little misleading. The 6”x6” or 8”x8” timbers aren’t intended to be a full seated bench, but rather a temporary perch while working in the garden plot (there are legitimate benches throughout the space for those looking for a place to rest). The wider edge also allows for placing hand tools (anything narrower and it becomes a balancing act).
The programming direction from the client was to provide resident garden space (nothing beyond that) and the ultimate users do not know that the apartments (or the community gardens) will exist. There are several existing community gardens in vacant lots near this development, with waiting lists for plots, which means demand is already there without the addition of this apartment complex. Hope this provides some context and some rationale for the decisions made to date.