Not weird at all actually. Water absolutely affects the taste of beers and famous brewing regions are often influenced by their water make up. Check out the brew science section of the forum if you're looking for more info on water. There's also some info in Palmer's How to Brew on the subject http://www.howtobrew.com/section3/chapter15-1.html .
Water composition is more important for all grain where mash PH is a concern, though certain minerals have other roles like accentuating hops, yeast health etc. There are literally entire books on the subject.
RO and Distilled make great starting points to add the necessary minerals too. Mineral/Spring or dechlorinated tap water are usually acceptable to brew with but for those interested it is recommended you get a detailed water report to see if your water could stand some adjustment. The sticky water primer in the Brew Science forum is a great place to start if the chemistry and math start making your head spin (I know mine did). Cheers!
It took me a while to tumble to it too, but when you think about it, water comprises the vast majority of the material that goes into your beer. Ergo, water is terrifically important to the taste of the finished product.