From their point of view, if technically possible, they would like to listen to any conversation and being able to spot in seconds conversations about any count

From their point of view, if technically possible, they would like to listen to any conversation and being able to spot in seconds conversations about any country security threat. It is easy to see that the risk is that if plaintext data is available, the data can be mined for a lot of other purposes including illegal or not ethical ones. It is also possible that eventually that data could leak to the wrong entities. And yes, in any big organization, the left hand may not know what the right hand is doing and, while one is concern in matters of public safety, the other may be primary concerned with the hegemony of its own power. So it is complex. But just assuming that you do not need them and they are just evil is a massive over generalization.