cripple the NSA, and you give free and secure communication to all sorts of undesirables. Allow the NSA unchecked, and make people transparent to the Government, (and worse expose them to typically stupid Government dragnet trawling).
That's a false dilemma. We have many more options than an unchecked NSA or a "crippled" NSA (though, note that taking away their ability to spy on US Citizens is only "crippling" in the sense that it would require them to return to their chartered mission as a foreign intelligence service...).
For example, most people aren't arguing that the NSA shouldn't be allowed to collect any of the sort of data they've been caught collecting. Just that it should have limited scope, and that they should have real accountability if they abuse their power. That neither cripples them (despite their claims) nor allows them unchecked, and that's just a simple example.
all electronic communications must be "tappable" unless you want to provide absolutely everyone with a safe channel for communication about their criminal, terrorist, or otherwise hostile business.
It's not quite that simple, even if it seems so on its face. When you make all communication tappable, you don't just allow the government access to communications of suspected bad actors. You also create something that can be abused by people in power (remember that the government is made up of people, and people do stupid things on a regular bases) -- from little things like a government worker using the capability to spy on a spouse to big things like government cracking down on dissent. And you create a system that can be attacked; if the US government can read your email, so can an attacker or a foreign government.
Keep in mind that the government is who defines what "criminal" is. If they have unlimited surveillance power -- even if it's only limited to "criminals" -- then it's a simple matter to change what "criminal" means until they can effectively listen in to any conversation they want. And quash dissent. Remember that almost every important campaign for rights involved "criminal" things -- from the fight for Women's Suffrage to the protests and campaigns for civil rights in the 1960's. These movements did "criminal" things in part to point out that they shouldn't be criminal things. To give the government absolute ability to stop criminal activity would be a very bad thing.