Some of those coins are just shitcoins. CMC should remove those inactive cryptos so that newcomers won't be confused and won't create unnecessary blunder specially when investing into altcoins. If only we just focus on few cryptos I guess there will be less FUD and more adoption. Some of those shitcoins created doubts to new players in the crypto market because most of them are just launched for the devs to profit.
No, they should keep every dead coin and token, so new people can get a good perspective of how many projects that managed to get listed have actually failed.
You can easily exclude tokens on CMC. I think it's ok that they list them all together because as long as they get exchanged for dollars and can hold all the properties of normal coins they are almost indistinguishable.