Well, I can say that the historical data for rep does exist in the database, so theoretically it's possible to display it. But vBulletin doesn't have any built-in way to do it other than that list on the UserCP. It is possible to change the number of recent reps to show on the UserCP (like change it to some crazy number like 100,000), but unfortunately it doesn't paginate it, so it would just make the page long and take forever to load for people who've accumulated a lot of rep. So, all that to say, the only sensible way to accomplish this would be a modification of some sort.
I think one of the reasons that the default is 5 is that it's designed to be a bit ephemeral and transient. Particularly when you get bad rep, the idea that it'll scroll out of view after a while is what most people probably want. It also helps people forget about bad rep received in the past, rather than looking back through their history and re-opening old wounds.
So all that to say, what you're proposing is theoretically possible. But I'm not sure if it's worth making the modification right at the moment.