I think of it like this: Ideally I would like to never use running water to clean my bike off, but there are times where the bike gets so dirty that hosing it off is really the lesser of two evils, the worse being leaving mud caked on all the components, rendering them useless. If the bike is just a little dirty, a rag and some elbow grease is sufficient.
Make sure the hose is not jet-streamed, and spray perpendicularly to the bearing location. For example, only spray the BB area from the top, as opposed to spraying sideways. You can also put the water in an old waterbottle and rinsing the delicate areas of the bike that way.
A very weak-stream spray will be okay for your bike-cleaning purposes.
I do it everytime I clean my bike. I use a chain scrubber with degreaser. Rinse it off. Rinse bike, scrub with light soap and water. Degrease rims, rinse off. Just use a soft stream. Then let dry preferably in sun with wind. Use a towel to dry also. Then lube properly the chain and other moving parts that need lubrication. Havent had any problems with rust or seals breaking or leaking. I do keep my bike inside, so it doesnt see the garage.