Appointing a committee seems unnecessarily bureaucratic, if the elders don't need the help. I also assume the elders are the most qualified to know what's important in an architectural plan.
Perhaps.
However, would it also depend upon what practical experience was in the background of the folks?
If deacons, who are skilled, in comparison to the wish list of elders, the practical servicing of the people may not be attended at the intensive level needed.
For example, what redundancy measures are taken, what lighting needs, wheelchair accesses, ... are all things the deacons seem to be aware because they serve among the people.
If I were involved (architecturally thinking - had to work through this a few times) I would gather a “wish list” from both groups. Formulate a priority list, produce a preliminary drawing, then revise it accordingly as both groups gave input.
But that is just my thinking.