I like having a selection of coats to rotate, depending on my outfit, weather conditions, and mood. Like Jeanne says, if I had to wear the same coat everyday, I'd get so bored of one coat after a season that I wouldn't want to see it again. Besides, our winters are variable enough that I might need a puffer one day, a long wool coat the next, a shorter not-so-warm pea coat on the next, and maybe just a leather jacket the day after.
At the moment, I'm feeling my longer, roomier costs more than the shorter pea coat styles, but I'm not getting rid of those latter ones because they are classic, in very good condition, and I like them. Coats are one type of item I have a hard time purging from my wardrobe.
As for silky shirts, I will sometimes wear them in the winter, mostly layered with a thin fitted silky tee underneath. I'm running warmer these days, so I'm moving away from heavy sweaters and toward lighter layers.