First of all the OP mentioned Thermawrap parka, not the jacket--- apples and oranges.
Regarding the jacket...
Like the lined windshirts (Marmot Driclime, Patagonia Alpine), you have all your (thin) insulation in one basket. It *is* a nice garment and handy on day hikes or a cool summer morning, but if you are cold, bringing gear that doesn't meet your needs is truly excess weight. A windshirt plus a Power Stretch, R1, or 100W fleece hoodie leaves you with a versatile kit.