I agree that typing out letters can be pretty tedious, but on the flip side, I always loved to write, so it let's me get in touch with my creative side. I also like to send letters because, I feel like I'm writing what's on my mind in a diary and I'm raising one of my favorite villager's friendship while doing that.
i send all 8 villagers a letter a day and completely write down random things. sometimes lyrics, sometimes riddles. oh and i've try sending a short message like "hi" and a villager told me that my letters is too short and try again next time like what cx