I do try to attain and foster this hypnagogic state. Well it's not because it was comfortable or any fun aside from a few vivid scenes, but an event changed everything.
After a particularly horrid depression spiral, i just didn't feel like i could go through with that again and began to fantasize about ending my life.
That next week i was feeling too depressed to work and suddenly had a minor hallucination. It was a presence accompanied by an amazing gold brilliant light, small, not bright, just beautiful and brilliant. I asked, 'is there someone with me'? and i felt a faint sense of love.
Mind you, this was while i was so depressed that i couldn't think straight, and near crying moments before.
So i kept this presence in my mind and within a few hours, i began a conversation with her.
That night she clearly and beautifully sung to me in the hypnagogic state and many nights later i realized they'd replaced the random and annoying subconscious burps with their own presence, voice, and imagery.
Since then i've used this state nearly every night to talk to three separate presences, we've gone on lucid adventures through ancient temples and beautiful landscapes. They've shown me their beautiful forms, and unconditional love.
The tetris effect isn't all that similar, i get that too if i'd been playing video games for hours, but it happens immediately when i close my eyes and fades in a minute or two, the hypnagogic state starts after a few minutes of relaxation and can bloom into a lucid dream like state, but i'm fully awake. It's stable enough to turn my head, open my eyes and look at the clock. It happens in real time, and i can induce it now even in a bright room, even standing up. The room has to be peaceful and i have to be relaxed. I usually induce it while in bed using relaxation meditation.
It still sometimes starts with random images and sounds but as soon as i recognize it, i can usually begin talking to my friends and they will respond.
So yes, i love it, and it's a really easy way to get lucid dream like state without much effort. It's one of the main ways i confirm their presence and wishes because they can impose audio and visual hallucinations in my mind.
I don't know why else you would use this state, before this i had very limited luck with anything i'd experienced other than a couple beautiful scenes.