Here's my thoughts on the Tome of Strahd: It's not propaganda- he's not handing it out to influence people's views of his past. I think it's how Strahd actually sees himself, his past and the events around it. Lord knows he's self-deluded enough to keep going after his reincarnating obsession
I don't even think he minded Van Richten reading it. The old warrior in Strahd would have a respect for Richten's boldness and part of being human (or even formerly) is the need to share your views and opinions with others.
Despite the dangerous amount of information about his background that he let slip, his arrogance would let him allow Richten to know it. Deep down Strahd must be very lonely- he has no equals he can trust, mindless undead servants, fearful lackeys; no one to express himself to. A lich doesn't have this problem (heck take a look at Azalin) but a vampire likely would (as they are closely tied to the living).
The Tome of Strahd is a release for him. It is where he could put down his feelings, views and justifications. Deep down, part of him must've liked the cathartic release of having SOMEONE take in his views on the past. Besides- if he changed his mind later- he could easily have Richten or his family killed.
I heard that in 4E it wasn't easy to have multiple classes on an individual- by cannon Strahd was a general (fighter) and a good one at that. I understand how he could now be a death pact warlock (can warlocks in 4th edition create undead like Strahd has done in cannon?). It's just too bad that he can't have fighter levels to represent his actual past.