Mostly because it rests on CA's and if the government can compel the CA to give them a signed cert for something that your security relies on, all they have to

Mostly because it rests on CA's and if the government can compel the CA to give them a signed cert for something that your security relies on, all they have to do is pose a MITM attack and you're blissfully clueless that they're spying on you. The whole system is broken and if you don't fix the foundations upon which your house is built, no amount of band-aids are going to keep the walls standing.