One of the best parts about ANR is the fact that you always have a chance. You can be down 3-6 as runner, with their winning agenda in an impenetrable remote, so you run R&D with your last few clicks and hope to find 2 agendas on top. Highly unlikely, but possible. Surely, this is one of the reasons why people have enjoyed the game and why it has been successful.
Horizontal decks get away from this experience because of their nature to snowball. Rather than watch your chance of winning as running decrease linearly, you watch it drop exponentially. Each turn you leave that Sensie on the board plummets your probability of winning into a dumpster. Watching your stock drop that fast isn't very fun; it definitely squashes your hopes.
To get better at Netrunner, you have to play games. Traditional/glacier games are fun because there's always a chance, so you enjoy the process of learning to play against them. Horizontal games are different, so it's like you're learning how the game works all over again, but this time the process is not nearly as fun. So rather than learn how to play against them, I think many players just give up.
I've personally really enjoyed learning to play against "degenerate" archetypes because I've adjusted my personal attitude. The mindset is:
"Once I learn to play against it, I'll have fun making interesting decisions."
It's kinda like learning to play against Scorch kill decks, or HHN. Once you learn how to do it, it becomes a strategic threat instead of an oppressive force.