[TL/DR]
If players have started changing their play style in order to increase the ARX they make, then this is because Frontier have created a system which has inbuilt balance issues. But I'm not asking for more ARX personally, OK?
[Long version]
Down2Earth Astronomy's video is a pretty good summary of why the current system (as far as we can deduce) works in a way that will always annoy someone, and provoke the kind of posts we are already seeing along the lines of 'I did such and such for x hours and only got y ARX, whereas doing so and so for just one hour got another player substantially > y ARX... its just not fair'.
If I'd been asked to design this system, which wasn't likely to happen I know, I would have said to myself. Playing the game is time spent in game doing stuff™ , so as long as a player is doing stuff™ , I can grant said player x ARX per hour spent in game (or whatever time period is convenient). So I'd basically build an intelligent timer that only increases the time it records if the player is actually doing stuff™ , and if the player goes awol and leaves his/her/its ship in dock, or supercruise, or orbitting a planet, then the intelligent timer would spot the player was no longer doing stuff™ and put the clock on hold. Even if some clever son/daughter/gender neutral offspring of unmarried parents figures out a way to semi automate playing the game to fool my not so intelligent timer, they only make 400 ARX a week, or 23 pence or whatever it comes to. Big whoop. Not worth wasting developer time putting together a system, like the current one, which tries to be too clever, and which comes with apalling balance issues. [Edit: I'm almost certainly not the first person to say something like the above, plenty of good coders seem to play Elite]
Simple example. If you're getting bored, you can skip this paragraph... Ok then. Exporation seems to reserve most of the ARX reward for play for when the player sells their cartographic data. You certainly don't make many ARX flying around and scanning things, but apparently you get 400 ARX for selling a mere 40 million credits worth of data. This would be fine if players could sell the data as they went (or at least weekly), but they can't. I've haven't been in a station since March (I think) and don't expect to see one until next February at the earliest, so I won't make any ARX selling cartographic data until AFTER weeks of play. But my two billion credits worth will only net me... 400 ARX if I sell them all at once, so even though I'm earning much more than 40 million credits of cartographic data a week, I won't get anything like the intended level of ARX reward. So much for players not having to change the way they play the game.
Well done Frontier, you made a nice gesture: to reward players for playing your game, but didn't actually consider HOW players play your game.
Now, please don't misunderstand me. I really couldn't give a flying squirrel for how many ARX I get. I'm just pointing out that Frontier have not achieved their stated objective of rewarding the player for playing the game their way, due to poor design decisions. Design decisions which may... and this is the icing on the cake... which may also be largely responsible for the large number of new bugs in different areas of the game. Tellingly, very few of those bugs seem to effect exploration game play!
[Disclaimer: We don't know how Frontier implemented their ARX reward system, but D2EA's video is pretty compelling. Anecdotal evidence from this forum is used to provide the figures for ARX generation I've used above. I do not know how accurate this is. I only know exploration has a comparatively low rate of ARX generation when no cartographic data is being sold]