It's not leeching like you're making it out to be though, we're monetizing our work, not your site, that's what I'm trying to say.
I'm sorry to say it but I'm pretty sure it's a general consensus that Blockland wouldn't be the same game without a modding community, if no add-ons were created, I feel safe assuming there would be a much smaller active playerbase.
Is that mutually beneficial? Like you're making someone who put 2-3 hours into a mod, and asking someone to watch a 5-10 second advertisement so they can get some sort of physical gain from their work, out to be an unethical leecher.
Your work only exists because of Blockland - the same can't be said in reverse. Sure the modding community is important but that's because it's members care about the game and the community and not the money they might make if they release something.
If you're looking to make money off what you do, go do it professionally or find a community that lets modders monetize their work. If you care about Blockland and want to make neat things for the community then stick around and do that - but don't expect or feel entitled to compensation for it.