I’ll just say it, Wi-Fi is shit. Bandwidth, ping, consistency and reliability are all better on a cable

In short:

• wifi can suffer from interference, especially in the 2.4GHz band where bluetooth and microwaves live too
• if you have older wifi gear or (small) iot devices and did not separate them, they could downforce the connection
• depending on the network interfaces, ethernet speeds can be up to 2.5Gbps for consumer, and 10Gbps for “prosumer” devices
• it is much easier to intercept wireless traffic, but it is generally decently encrypted nowadays (wpa2/3)

So it depends on what you want to connect: is it fixed, or mobile? do you live in a cloud of wifi? what about speed, security? Yes: It will make a difference , it is up to you to decide whether it’s worth it.

Certainly not. Wifi lacks the bandwidth 1 Gb Ethernet has. If you have multiple devices, they all share the maximum bandwidth of Wifi, which is typically around 700Mb total, compared to each device getting a full 1Gb on Ethernet.

No it isn’t pointless and yes it will make a difference. An Ethernet cable isn’t going for half its bandwidth when a microwave turns on.