I have little doubt that most people who talk down on his work haven't actually read it. It may be a lot of rehashed information with a dark edgy twist to it, but there is a lot of very useful information in his books, and they're well written imo. I haven't really read much of his post-BALG work, but I would consider his Works of Darkness trilogy(WoD, Baneful Magic, and Evoking Eternity) to be full of useful tech and info for a lot of people. For example his demon sigil charging technique, it's very well presented and can be very effective. It may not be the "proper" use for a spirit sigil, but it's a much better method than the zero-effort offering and saying a prayer to one that I see a lot of demonolaters doing nowadays.
My general opinion has always remained that these books are not a bad place for someone to start, so long as they don't get too caught up in all the dark fluff. Side note, even though I'm defending EAK here, that become a "double crowley" book that pokes fun at him and others like him is a hilarious read.
One of the most interesting books of his, imo, is Kingdoms of Flame. While almost certainly frabricated and egregoric in nature, it is a well thought out system. I had fairly strong and fast contact with some of the spirits listed there, as did quite a few others I knew back before the BALG forum even existed. I don't know if more of this system has been presented in his more recent work. I do know that the Book of Azazel presented lots of similarly constructed spirits, but the current of that system seemed entirely different. KoF as it's own thing seemed internally consistent, unlike Azazel which is trying reshape existing ideas and stick a bunch of new ones in there. I don't know whether these systems and their spirits were fully invented by Koetting, or whether they were channelled or revealed through his work with some spirits, but in practice it doesn't really matter either way. I would at least suggest they're interesting enough to take a look at, and wouldn't rule out revisting them in the future myself.
I think it's bullshit that he was deplatformed on social media, just because some idiot who murdered women for a pact to win the lottery was a member of his forum. I also think it's stupid that people try to discredit him by talking about his personal life, legal issues, and drug use. Some of the smartest people I've ever met were drug addicts who lived in squalor, and I've known multiple magicians who were very legit and wise and also ended up living on the streets, battling different demons than the kind we usually talk about. There isn't some perfect way that someone's life has to look for them to qualify as a serious practitioner.
I talked a bit with EAK many years ago, not sure what he or his BALG crew have put out recently, but he's definitely a legit practitioner. I don't think what he's done is much different than Damon Brand/GoM in rehashing a bunch of material and giving it a different flavor, but at least with BALG there are actually multiple authors, not just one guy writing books under different pen names. It's easy to form a negative opinion about EAK as a person, look at his marketing and write his work off as a scam before you read a word of it. But I find it funny that the people who do this are often the same ones who would champion something like GoM as if it were something revolutionary.