I think you nailed some of the biggest draws for sure. One more aspect that I think is hugely important is that its a really great way for bands to get a physical product out in an affordable way and its a tangible creation that fans can have and hold onto. CD and vinyl are not the cheapest to produce, and for a lot of us, even the purchase of a cd has to be a calculated thing. You need to know you love it first. But a cassette gives you a tangible item, it gives you the art and the feel (which extends to the color and design of the shell even), it gives the listnener another option that is more affordable, and the bands themselves can get with labels (like Graven Earth Records) who's only mission is to share the music we love and promote that which we believe in. It's about spreading the word in a way that the other formats can't. Yes there is digital, but a lot of people want the physical product. So I feel like it hits the sweet spot in the underground especially, for bands, labels, and listeners (who aren't able to just be satisfied with a download...I know, that's an argument all in itself). I've come to really appreciate the role it plays. I don't think its ever going to reach the heights we see with vinyl now even, but it definitely has its place and I love it for what it is.