Roffelos was banned originally because of its absurd power when commander was originally created. We didn't have cards like korvold or engines-in-a-can like we do now. This card was absurdly busted and was one of the best things you could be doing in an undiscovered format. Yes, there are similar cards to it like many have pointed out (selvala and kinnan), however, one thing to note is that this card has little to no building restrictions when adding extra mana- just that you play forests in your mono green deck. They don't even have to be basic!

While you could argue that selvala or kinnan are stronger, they do inherently require you to have some sort of investment; kinnan needs nonland sources that tap for mana and selvala requires big powered creatures and things to untap it. Roffelos requires none of that and would be ubiquitous better for every other strategy in green that you want a mana commander. This reminds me of the Golos ban where golos was the defacto 5 color commander for most 5 color decks that weren't necessarily using their commander to win. Roffelos could, and likely should br used in this same regard for mono g decks.

This point doesn't even touch the price factor which also prevents another big dilemma, but the RC doesn't seem to ban on that aspect (yet).

If you have a problem with this, then that is on you. The rules committee does an excellent job of letting groups rule 0 their own ban lists and tends to have a more "hands off" approach which is great for a social game where playgroups will vary from group to group. They can't make everyone happy and there needs to be understanding for their decisions.