Um Why get a hearing dog? Not to threadshit, but I mean I've never really understood the point of a hearing assistance dog. It alerts you to sounds and stuff but so do hearing aids (they don't always)/CIs (don't know about those) and just using your vision (it's a lot of work and can stress you out).
While people tend to realize there are different levels of hearing loss (mild, moderate, severe, profound), I don't expect that everyone realize the effects that it has on some people. I expect I don't know everything about the effects of deafness on people. So here's my experience.
I grew up deaf
(although was labeled hearing impaired/hoh), was mainstreamed, and given HAs. I had my twin sister to help with things I missed (and I didn't realize how much until later
). After college, I moved out on my own. I found out that I could understand someone to a degree in normal speech (with no to little noise) with the latest and greatest HAs. I could also hear some people on my cell phone due to its volume control (turned all the way up).
However, a lot of the time I still can't hear the phone ringing, people knocking on the door, my alarm clock, people trying to get my attention from behind me, and other alarms and bells and whistles (ie microwave beeping, kitchen time, etc). I missed phone calls from friends/family, missed visitors/other important guests, burned food, was late to work, annoyed the people trying to tell me something from behind, etc. :-o
I also cannot locate sounds that I do happen to hear (ie if my phone rings and I happen to hear it, but don't remember where I put it, I won't find it by sound). That started stressing me out, so I was using my vision as almost "double duty" (ie trying to look every at once to see if anything is making a noise that might be important) and that stressed me out more, felt like being on "high alert" every second of every day-I didn't want to miss out.
So I rescued a young dog with a good temperment, found a local dog trainer with experience in training service dogs, and she instructed me in training my dog to alert me to sounds I don't hear (there's tricks to it). Compared with the several years between college and service dog, it has been a life-changer!
how does my post indicate anything about society's views on deafness? 
deafdyke suggested flashing lights and other technologies could serve all needs -- I gave some situations where someone might not have flashing lights and other alarms installed, but could use a service dog instead. Never told you that you need any of these: flashing lights, video phone or other tech or dog. No need to try to force a brawl.
