Shower or no shower depends on several things and it is not carved in stone. Just whatever or whichever way/method suites you.
If you have your bin outside in the yard, it is practical. No mess. It also depends where you live. If you live in Seattle for example, where they say it rains 360 days/year then it is not favourable because the bin will stay too wet and it will invite problems. Lots of mites for one. Another, stuff can get really compacted in a wet bin and that means less air pockets >>> not enough O2 >>>> smelly bin >>>> you might get SOP (string of pearls = protein poisoning. If your bin is a Flow-Through (FT) and you live in a dry and warm climate, less problems.
However, my logic is against showers for worm bins. You keep flushing the good stuff including MO etc., that will slow the composting process down. Whenever I find that the top layer of my bins are rather on the dry side, for the 2x4, I use one pass of the garden hose on the gentle shower setting. For the RM I use spray bottles.

If you do need the "good stuff" for your plants before you are ready to harvest, I'd suggest you get a handful of stuff that looks the most ready and "slosh" that in a bucket. Return whatever is left at the bottom, back to the bin.
Just my 2 cents.

One poster on the site does use a water harvest method. He has carefully devised a system for his needs. It seems to work perfect for him. More power to him. He should keep doing what works. I am glad he posts about it. Maybe it is the way of the future for vermicomposters.

For all the other vermicomposters who are not experimenting with his method I say the bin should not have leakage and if it does then add more dry bedding and pour the leakage back on top. Not all leakage is perfect food for plants. Possibly it is just vegitable and fruit fermentation juice. The value of it is to wet bedding at the top of the bin and spread the wee beasties quickly to the new food additions.

Worms can live in 100% water forever. The water has to have oxygen. Worms can not live in compacted wet bedding with no air. Bad things happen. With worms, bad things smell bad. Thus the interest in fluffy bedding material. Also why we post endlessly on shredders, peatmoss, coffee grounds, coir, etc. The food is just nitrogen. The bedding is air supply and surface area along with moisture moderator. IMNHO the instructions on the worm cafe should of said if the bin has leakage then it does not contain enough bedding. Adding food and not adding bedding is maybe the #1 reason bins fail. The only reason to even add food is to process that bedding through the system. :-)

I add water, about a bottles worth, if the system seems dry and I have not, or do not plan to add wet, juicy food in a few days. I think I should air out the water for 24 hours to let the cholorine evaporate. We do not have the non evaporating choloramine or whatever in our water.

Thanks everyone - I will stop showering my worms (and conditioning their long blonde hair). I now understand that I am washing away microbes that they need to eat etc.

I am learning so much here! You all rock!

Good luck Deetoo. It's a pleasure to answer your questions since you gave us good info to work with.