IHMO, speed matters in wireless networks but not for the reasons everyone thinks.
The main reason speed and latency matters is that a cell tower is technically a bottleneck. It can only accept a limited number of connections and once those connections are maxed, things will start to slow down. So the key to handling more customers in a limited number of connections is to get the customer connected and disconnected as fast as possible so the next customer can get on.
In an extreme example, let's compare a 200MB file download over 3G vs LTE. For PM 3G, the max speed is 3mbps, so a 200MB file is 200MB*8=1600Mb/3=533seconds. So the customer is connected to that cell tower for 533 seconds to transfer that file. With LTE speeds, let's assume the speed is 100mbps, so a 200MB file is 1600Mb/100=16seconds.
I'm oversimplifying the way customer connect to towers as there are some wizardry going on in the background that can increase the customers connected given a limited number of connections, but the fact still remains, the customer on 3G, will be connected to that tower far longer than on LTE.
So, when 5G comes around with wireless speeds exceeding 1Gbps, a customer doing the same 200MB file would be connected to the tower for less than a second... The faster a customer can connect to the tower, get their information, and disconnect, the better it is for the tower.
EDIT: What determines the max number of connections available to a tower? In the most simplest sense, I believe it is the spectrum frequency and the how much of it you have.
