exactly decreasing number of using ERC-20 was one of the reasons why ETH gas fees going down these days well aside from the fact that it is the main concern of many of us it is also one of the reasons why other blockchains and bridges were trying to resolve, to give the crypto user a low gas fee which will not go to cost them an $8-$14 or more just for transaction fee. I think we shouldn't worry about why ETH gas fees going down because personally this is what I am looking for because there are other transactions that I have no choice but to deal with the high gas fee of ERC-20.
Decreasing number of tokens? or maybe decreasing number of eth transactions? anyone can create an erc20 tokens but not all are going to use it, that is why I don't think the number of tokens has an impact on the fees. No one is worrying about the present case but they are only curious on why it is happening.
If there is one thing that people are worried about, that is if the fees soar high again but the logic behind the fees are simple. All just needs a common sense to figured that out. Fees of eth might have drop dramatically but for me it is still expensive, sorry eth I won't still use it even though I have a token that I want to sell.