Connect one cable - get power, mouse, keyboard, display, audio, headset, webcam and possibly Ethernet or a Time Machine backup volume connected with a single cable.
...and how does having a couple of USB-A ports
stop you doing that?
Nobody is asking for Thunderbolt ports to be removed. TB3/USB-C and USB-A have lived happily side by side on iMacs, Minis and Mac Pros for years. There may be an argument for removing USB A from laptops (because having your laptop 2mm thinner is far more important than having a useful selection of ports)
For a long time, I had a very nice 27" Cinema Display on my work desk and - without the "magic" of USB-C it needed a 3-headed cable with MagSafe, MiniDP and USB plugs. I remember the gruelling
three seconds I wasted, twice a day, plugging those in - Oh, the humanity! It was such small consolation that, when I got home, I could plug three different devices into the same three sockets without having to spend $300 of my own money on a dock...
5 Gbps of USB (plus the video output)
Except... only expensive Thunderbolt displays/hubs or the very newest USB-C displays (that support DP1.4 with DSC) actually allow that - most displays need all 4 pairs of a USB-C connection to do 4K@60Hz with DisplayPort 1.2 and can only support 480mbps USB 2 speeds alongside video. Most non-TB USB-C hubs with display outputs only support USB 2 downstream.
...and even where that
isn't a problem, the 5 Gbps of USB has to be shared between all the devices connected to that dock - plus the added latency of going through a USB hub.
NB - I currently have a M1 Max Mac Studio with 2xUSB-C/3.2, 2xUSB-A, Ethernet, SD and HDMI. That's pretty good - but I use them
all - there aren't any spares that could be sacrificed to a smaller box, and I
still use a hub - which can drive 'don't care' USB devices leaving the host ports available for critical kit like audio interfaces.
Why get rid of it?
I mean, OK, if you're planning to replace it with an extra full USB-C port that supports displays - but that's not the way it usually turns out.