You'd have to weigh out the pros and cons tailored for your application and then decide if it's worth it. Also, you want skinnier winter tires for maximum snow traction. Less is more in this regard.
I've only seen lifted WRX's, Baja's, and STi's done in environments where those people also go off road with their vehicles. I personally think the car has enough clearance as it comes from the factory on the stock suspension.
I'm not familiar with how everything changes when you lift a car. However, aerodynamics, fuel economy, handling are guaranteed to change in one way or another, whether positive or negative. Lifting would mean a higher center of gravity, so I see more negatives than positives, if any.
-What's the cost in parts for the kit?
-What's the cost in labor for installing the kit? (Null and void if you're going to do the work yourself.)
-Is 1" going to make much of a difference, truly?
This is extremely interesting!
2004 STi ground clearance is 5.7".
2011 STi ground clearance is 6.1".
2019 STi ground clearance is 4.7:.
Your other option is to get 18" rims that clear your 2019 STi (I don't remember if you found wheels or not off the top of my head.) and get a higher sidewall. So, for example, instead of 245/40R18 tires, you could go with 245/45R18 tires or 50R18. You have to use a wheel calculator to determine how much of a difference each aspect ratio gives. It'll also make your speedometer inaccurate by a small threshold. From personal experience, all of my cars have always been slower in a speed trap than what my speedometer stated by 2-3 MPH. So, I always factor that difference when I'm driving. If you have a fixed speed trap somewhere close by, I'd drive 5 over the speed limit and compare the two.