Obviously, you've never played a cloaking class, so your opinion on how unfair they are is irrelevant.
I play cloaking classes AND a class with Stealth Scan, and have a decent knowledge on how to play them (meaning: I suck, but I'm not terrible). As my Scoundrel, I must use every trick I have in order to pull off an escape (but is, honestly, the most fun because of that fact). As a Vanguard, it's pretty simple to pull cloakers out of stealth with DoTs or Stealth Scan (too easy, in fact).
Now with a tanking cloaker (Shadow/Assassin), I agree it's pretty ridiculously easy to do a ton of damage, tank, then get out of combat. But only because they're a tiny bit overpowered at the moment. My Assassin is really dang fun but I know that it's because I'm OP.