You're probably just putting yourself into bad situations or playing too aggressively. Most people I see dying to nades (me included) are those who are too eager to chase someone around a corner after getting their shields down. Now the kamikaze sticky guys who will just toss their plasmas even when they have a perfectly good chance of fighting back with other means, that is annoying, no doubt. But those guys usually miss unless you just run in straight lines like a nub.