2.4GHz wifi is not suitable for two big reasons, interference and low bandwidth. 2.4GHz wifi in any kind of suburban or city environment and sometimes even in rural will be congested with other networks, microwaves, other appliances, etc causing massive speed degradation or fluctuations. The range of 2.4GHz is just too large for all the equipment that uses it in today’s world. In my previous apartment complex for example my phone could see 35 distinct 2.4GHz wifi networks while only 3 at max can operate without interfering with each other. In that same building i could only see 13 5GHz networks. Which brings me to the second issue of bandwidth
2.4GHz at least here in the US only has channels 1, 6, and 11 that will not interfere with each other. if anyone puts their network between these three channels it will knock out both the one below and the one above. Channel 3 would interfere with both channels 1 and 6 for example. By going up to 5GHz you have many more free channels, fewer networks competing for those channels, and higher bandwidth channels allowing for much higher throughput. 2.4GHz allows 40MHz wide channels which in isolation would offer ~400mbps, but you will never see that in the real world.
Personally, i think OEMs should just stop including it or have it disabled by default and only enable it in an “advanced settings” area.
Edit: I am actually really surprised at how unpopular this opinion appears to be.
Here’s the thing. There are still plenty of devices that only have 2.4Ghz radios. There’s some cheaper stuff still made today with just 2.4Ghz. So you’d just cut out a load of devices from working straight out. This kind of thing needs to be done slowly. 3G was very different because phone makers generally always want the more modern technology and phones that didn’t have radios capable of 4g or better really are just rare now.
But, there’s also just no reason to. Have 2.4Ghz available doesn’t hurt you, if you’re not using it. Any chipset with 5Ghz is not costing more to also support 2.4. They’re just all pretty much single chip solutions these days and the aerial is usually just a coil on the board somewhere. If your device works on 5Ghz it will use 5Ghz.
I’d also argue in real terms 5Ghz isn’t much better than 2.4Ghz in terms of channel space in places that need to respect DFS rules you generally only get one 80Mhz channel that will definitely work, and if you’re using 802.11ax 80Mhz is really the minimum you want to get even remotely close to the advertised rate. Everything else useful is either DFS or limited power (at least here in the UK, and I don’t recall seeing the limited power channel as an option). Now, I’ve generally setup two wifi APs in my house, one on the only non DFS channel, and the other on a DFS channel. That way if the DFS channel gets knocked out there’s a fallback to the already congested “main” 5Ghz channel.
I think the main point is, why remove something that doesn’t really affect you but may well affect others?