Although most people appreciate the comfort of riding a bike with a suspension fork, orthodox cycle tourists are sceptical about it. However, I believe it is pretty useful when it comes to bike touring. First of all, it is very rigid when we start swerving while riding fast with a loaded front rack. In such conditions, a rigid fork behaves as if it was not rigid at all, moving from side to side, becoming noticeably less comfortable and increasing the risk of fall. Certainly, there are good aluminium forks which are really rigid, however they are quite expensive and rather hard to find. Moreover, once you drop the luggage and accessories, a suspension fork allows you to cycle off-road. Of course, then we need to have harder elastomers or springs to avoid "bowing" with each use of brakes.
Special front racks for suspension forks are on sale.