I am in an active, mid-size FC with a strong core of crafters. Getting four people into the workshop has been possible for us most of the time. If the requirements were any stricter, I think we'd be in trouble.

Every time we put out a call for crafters, the majority of our members who are online are:
Waiting on a timed node, Vista, fish etc.
In a dungeon queue
AFK
In an instance (the most common)

In other words, they are playing the game, and having to stop and come to the workshop is an inconvenience (fortunately one that they are willing to put up with).
Having to sit around AFK while someone feeds materials into the machine is not engaging or fun, which is why I'd like to see the four person requirement lifted.

Tightening the rules may stop some people with single-person FCs from crafting but it will also have the effect of making FC crafting a lot more tedious and difficult for FCs like ours. There is very little content for FCs to do together, let's not suck all the fun out of this.