I have eight of these Honeywells running in a couple of vacation rentals. I let guests know to run them till dry before refilling, and I make sure they don't sit wet between guests. I also run a large Holmes wick humidifier at my home. I've run the Honeywells for several years now, and the large Holmes for twelve years. In all that time, I've only had one episode of significant mold growth on a wick, which occurred when I accidentally allowed a wick to sit wet for several days on end.
If the wick stays wet for many days or weeks, it will mold. This is not a design flaw. It's unavoidable biology.
Also note that the UVC "disinfection" system in these Honeywells is useless. It might disinfect the tank water in transit to the wick, but that does nothing to address the innumerable bacteria and fungal spores supplied by the air passing through the wick. What the UVC lamp does do is slowly destroy the plastic base, so I always remove the UVC lamp when I buy one of these humidifiers.
I agree the fan should be more accessible, but it can easily be blown out with a computer duster or compressor.