This isn’t an uncommon sentiment to hear from me, and is usually triggered by WG doing stupid things with replay files.
At least, I consider them to be a bit on the stupid side. YMMV, though.
So what brought it on this time? Well, it’s like this… missions are now implemented, which is nice. They can give you extra XP and credits – but I’d need to display them as well, right? So a bit of battle result digging turned them up as ‘event XP’ and ‘event Credits’. This on it’s own is already odd, since if there is an event going on that does give extra XP on certain tanks, and you’d do a mission with it, you wouldn’t know where exactly all that event XP came from.
You could say I’m picking nits, and in a way I am because I can still display values correctly, but it would be a nice feature to be able to say “Joe Q Random tanker dude earned 500xp, and another 500xp because he completed the ‘oh jesus kill them all’ mission”. So some more digging turned up this when you actually complete a mission:

'questsProgress' => { 'SEA_01-01_Oct_2013_q1' => [ undef, { 'bonusCount' => 4 }, { 'bonusCount' => 5 } ]}
Right. Now I know that those two bonusCount entries are for ‘reward for excellence’ missions; the damage done and the damage via spotting. But, uh, how would I know that from seeing ‘SEA_01…’ there? I wouldn’t. There’s no way to get your hands on that data short of scraping some cache files that get created when the game runs, and that would obviously only get me the ones on the server that I play on.
Happy, joy.
So probably there won’t ever be any detail view available for how your XP was obtained short of “this is what you got, this is added cos you have premium, this is added cos of your daily double, and here’s your event xp”. Would’ve been nice to have some sort of, I don’t know, better way to get at it. Typical WG fashion though; it always does seem to me that the first thing a new intern gets to do is fuck with the replay system some more.