It was also used for formally entertaining guests and wedding receptions. It was where the expensive furniture and good dishes were kept, that you didn't really use except when trying to impress people. So yes, it wasn't for families who lived in a one room, dirt floor hovel, or families that had servants and many formal entertaining rooms that they could afford to use regularly and maintain, but if you were middle class and had enough for a "good room" that you wanted to "save for best" then that was what it was used for. https://www.simplysoldaz.com/the-death-room/

Also- 30% of people died before the age of 5 in 1900 England and USA, so it's not like they rarely had occasion to use it.

There's a part in one of the Disc World books by Terry Pratchett (which are fiction, but roughly analogous to that time period in England) where we are being introduced to Granny Weatherwax (a witch) and it is said of her that she never ever uses the front door of her own house, because that is for brides and corpses and she didn't plan on ever being either of those.