Cell phones stink when you are talking with people with hearing issues.
Heck, cell phones stink many times for non-hearing impaired calls.
This is why we haven't dropped land line yet. We have family who have impairments both in hearing and cognition. It just adds another barrier to have a bad connection.
Worst yet, many times the bad connection is just one way. You may hear everything find, but on the other side, it sounds like you are talking under dirt. Please remember this when you call me with your phone and I sound fine. Guess what, you don't.
Sadly, this has been a trend in many cases. "Just give it to me for free, cheap or easy, and I don't care what it looks like or sounds like."
That said, we'll probably be dropping landline soon. Cell phone voice quality has gotten better and will continue.
VoLTE is rolling out and will help.