I'm sick and tired of people quoting this. Quite frankly, telling people to not upgrade their brakes when they add power is ridiculously dumb. When people add power they use it, whether it's passing people, doing pulls, canyon carving, swerving in and out of traffic, or even street racing (yeah, it happens). Saying that they should double their whp and not do any brake upgrades is asking for trouble.
Now, with that said, only dedicated track cars (or Alex Roy) need big brake upgrades. They are a complete waste of money for 99% of the people. Rotors, in general, are not needed. Better pads? Yes. Lines? It's a safety issue. It does help the feel of the brakes though. Fluids? Safety issue. In my personal experience this is the most noticeable difference in pedal feel over everything. Good fluid makes the brake pedal so consistent with pressure it's amazing.
Plus, I'd argue that 02, 03 WRX's in particular could benefit greatly from brake upgrades. I warped my rotors on my 02. I upgraded to WRX 4 pots with street strip pads and the H6 upgrade in back. Now, the feel of it was drastically better. Do I stop quicker? I don't know, I really wish I would have tested it before and after. Do I have much greater confidence in my braking system and brake later in corners? Yes, hands down. Plus I am no longer worried about doing repeated pulls (say, for logging), canyon carving, or track days.
Alright, here's my biggest issue with telling people not to upgrade brakes at all. If you do one high speed run, or even just pass one person, you can accelerate so much quicker with twice the power that you go much faster than when the car was stock. So instead of passing someone at 70 your passing them at 90, during a high speed pull instead of letting off at 100 you let off at 130 (or 150, or 160), trying to show off to your friends (or a girl) you decide to take on a muscle car on the freeway and do repeated pulls against them (or worse, repeated ricer flybys). I know these things happen, especially with young drivers.
So, how many pulls can you do with stock pads, fluid, lines before something breaks? A lot, but I have no desire to find out the exact number.