Just a thought that occurred to me while musing on the Loveletter - if the viewpoint that Truth is Violence is the case in Mundus, and Truth can be spread via Speech, does that mean that all Speech is Violence (as they are all expressions of a Truth, the power of said truth is conditional only on the speaker's ability to make it so, and thereby has the potential to become as Thu'um?
And as a result, this explains why dragonspeech is powerful - dragons are the children of Akatosh, who is Time, which is the ultimate imposition of a universal Truth. Dragons, connected to that Truth, thereby have a greater ability to impose their own limitations on Mundus, and so have Thu'um more naturally than other beings.
Does this make sense, or am I barking up totally the wrong tree?