Oh wow, that isn't very many you're right.
Plus side, the ones we're getting seem very promising? I loved Uncle Samsik (not for everyone but I enjoyed it a lot) and I've been looking forward to both Won Gyeong and Queen Woo for around a year now.
(Also Pachinko but I need to check out the first season too).
It is curious why there are so few - I love a good sageuk.