I live in an a rural area where there are only two trunked systems to listen to and I need alphanumerics to follow the communications. One has 42 talkgroups, of which only 20 are used often, and is operated by the Mammoth Mountain Ski Area. The other is Southern California Edison's where I can hear about 30 used on a regular basis. I have one radio without alphanumerics that I keep next to the bed for times when I hear sirens or want to wake up listening to the choreography of departments getting the ski area ready after a significant snowstorm with the ski patrol firing off the avalanche guns. It is really tough to remember all those talkgroups by number as they flash up very rapidly. I have a chart on top of the scanner but I can't look things up quickly enough to keep up with the action ("let's see was that the snow removal people or the snow grooming people getting that announcement"). I don't listen to the ski area every day because I only want the info from it when there is a storm or when I see lots of people at the hospital and know it is a high injury day. So any memorization is quickly forgotten. Additionally the numbers are very similar (it is a Type I system) with 000-03 getting confused with 001-03 and 201-01 with 200-10.
The conventional systems in the area are few enough that I often listen to my main scanner in the upstairs office through a wall mounted speaker in my garage/workshop. I can tell which agency is speaking just by listening to dispatcher's voices and the sound of their systems, each has a signature background sound and audio characteristics. I'm only listening to 15 agencies maximum so it is easy when you combine 26 years in the same county. But I live in a very sparsely populated area by most person's standards with only 30,000 people living in a 220 x 75 mile two county area. Even at that I prefer alphanumerics. This reflects normal day to day traffic, but when wildfires occur or significant weather comes in I"m also listening to business frequencies and command/tactical frequencies. I sure need alphanumerics for those times.
All my frequently used radios have alphanumerics including my ham radios. When traveling, which is some of my most enjoyable scanning, alphanumerics are essential. I do most of my programming ahead of time in the winter and use the laptop to enter new programs into the low capacity scanners and have files and files of programs made up for the specific areas I travel to. Without alphanumerics I would be back to carrying 5" x 7" notebooks with the programs written in pencil and having to look at them frequently.
Software, alphanumerics, scanners with thousands of channels, and the systems similar to GRE's V files are necessary to keep up with the incredible growth in radio systems. 30 years ago you could monitor the L.A. Sheriff Department with 10-20 channels in a scanner and memorizing the frequencies was not so difficult as they generally only had two places past the decimal, such as 39.82. Now with most frequencies having four places, e.g. 483.7125 and 483.7875, it isn't as easy for the brain to recognize the differences. Now the L.A. Sheriff's system has around 50 to keep track of, if not more.
You also should keep in mind that other members of your household might be interested in listening to what is going on, sometimes when you are not home to interpret using your vast memory, and alphanumerics allow them to understand what they are listening to.
A radio without alphanumerics might be cheaper in the store, but is more expensive after you get out the door due to the conveniences lost over the life of the product.
