Both. When you're hungry, it will be a nuisance. When you burn the crops and/or steal the food stores of your enemies, leaving them desperate and starving as the campaign rolls into winter, it will be fun.
I don't think it's a matter of either or. The alternatives are not "craft heavily in the campaigns or you're hiding in the EK's".
The beauty of CF is that it's player driven and as such you can't really enforce priorities among all the players. Some players will find value in crafting in both campaign and EK (there are alts...) and some will pick one or the other. There are as many ways to be "best" as there are players.
Best crafter to me is all well and good but I'm much more interested in crafters finding meaningful experiences in crafting in CF. I am looking for challenging, exciting moments as defined by the players, not by whatever may be the current trend on the boards. I want crafters in CF to rage against the resources, to stretch their brains around combinations, to frantically craft as their guild stronghold is crumbling around them but they're still getting the gear out even against the odds cause they know they'll turn the tide just with their skill.
I want crafters to create grids and reference materials and pore over combinations. I want them to sit quietly and mull over how to strategize the promotion for their trade hub. i want them to woo other players, to lure in patron guilds, to develop networks of crafters and merchants, to ride the waves of supply and demand with such skill that they're legend.
I don't care where people craft. I don't care how they do it. A crafter in their EK is not hiding and a crafter in a campaign is not a drone. It's sandbox - every player gets to play how they'd like to and we here on the boards don't actually get to decide how good they are based on where they're crafting.