Having lived without, and then with, and then again without a water softener, I must say that I agree with BrewerGeorge that the feeling your friend is feeling is most likely one of perception.
You should ask him to turn his faucet on and rub his hands together under the water (just his bare hands without having used soap or anything), and describe to you what it feels like. The reason why I suggest that he do that is because when we got a water softener for the very first time, I would love doing just that, because the plain soft water itself felt so slick and 'lotiony' on my hands, compared to the 'squidgy/squeeky' feeling I was used to with our hard water. It was a feeling that we had to adjust to, but since it felt so nice to me, it didn't take me long to make that adjustment (it took hubby a little longer).
Right now, we are living without a softener (I really miss it) and I am forced to add a chelator (EDTA) to my formulas to help cut down on that tacky/squidgy/squeeky feeling when rinsing off, which comes from the mineral scum that forms from using my soap in our hard water.
A good example that highlights all the above is one of my ex-in-laws. He's no longer a part of the family (ugly long story), but when he was still a part of the family he couldn't get enough of my soap. He absolutely loved it and was one of my biggest soap fans. At one point (while he was still a part of the family), he moved into a house that had a water softener (his previous house did not have one)............Anyway- when he used my soap in the new house with the softener, he asked me why I had changed my formula (I hadn't). He said it didn't quite feel the same and that it rinsed off differently than what he was used to, like he couldn't rinse it all off or something............... I had to explain to him that it wasn't my soap's fault- it was because he was not used to a softener........
I went over there a few times to watch the house while he went away on vacation, and I took some of my soap with me to see how my soap performed in their soft water (because we had actually been without a water-softener ever since before I started making soap), and it was awesome! The bubbles were amazing and there was no squidgy feeling when rinsing off- everything rinsed off nice and smooth with no residue. Yep my soap behaved differently, but to me the difference was a good thing!
All of that was before I started using EDTA in my formulas, btw. With the EDTA, my soap lathers better and things rinse off more smoothly. Although the results are not on par with the results I got from the softener, they're still not too shabby if I do say so myself.
IrishLass