I get that the prisoner thing is "tradition," but yknow what, maybe it's a [censored] tradition.
Yep, I said it. I'm a heretic.

But every single title, people make an alternate beginning mod. Why? Because the people that play these types of games don't want a backstory; they wanna make their own. Hell, I'm sure many TES fans were livid over the backstories that the Lone Wanderer and the Courier got in both Fallout titles.
And that's the issue: a prisoner? That's a pretty big backstory. I mean sure they don't expand on it, but they force you to justify your arrest, which for Paladins or white knights? ....Yeah, sort of an issue.
Skyrim handled it the best in that you're literally arrested for nothing more than crossing the border during a civil war battle, so it's easy to say your white knight was simply at the wrong place at the wrong time, but I think continuing this trope has a tendency to get in the way of roleplay.
Many of the alternate beginning plug-ins seem to allow for customization regarding your starting location, wealth and equipment. Perhaps adopting some of these ideas in future games would be a welcomed change.