Agreed. Suspension tuning for performance/handling is a very meaty subject.
Spring kits are primarily for road cars and are generally fine within road speed limits. For the track, you'll need way stiffer springs/dampers to keep the car up round corners, and marrying the two disciplines into one package that does everything well is very difficult. That's why I will never track my car. It's better to have a Caterham for the track, and a Golf for the road
I'm with you on that. Even some modern coilovers are way too soft for track driving. Back in the day - as I'm sure you'll remember - coilovers were designed for the track. You really knew about it on the road. Horrible.
The suspension companies cottoned on to the market for a kit that achieved a big drop but without the harshness, and that's pretty much what we see today in a certain price range. It's what I'm on. My car is quite comfortable, and low, but I'd never expect it to manage on track.
Anyway, back on topic. OP, if you're going lower, you really want to be matching the springs to some uprated shocks, like VWR or Bilstein. Coilovers will do the same job, but obviously with the ability to tweak the ride height.
You can just stick some lowering springs on with your standard shocks, but what seems like a similar ride quality to standard for the first few thousand miles quickly degrades into a rough, fidgety ride. Plus you'll struggle to get much of a genuine performance increase without some uprated shocks.