It's really interesting (by which I don't mean bad) to see how different the game will be on release compared to when I signed up for the early access. I've never really been part of this type of community feedback based design before.
My understanding is that with the new proposed system, if you really only like mining, you could complete all the mining objectives and then just do mining themed dailies to reach the level cap. That sounds great (I don't think I ever would, but having option is a big bonus)!
While I would REALLY like all tasks to be 'active' and available to work on instead of just having to pre-select 5 (as nevir has already suggested), I would hazard a guess that that's a technical limitation (It's efficient to check whether any action fulfills a requirement for any of 5 tasks, but to make it so that all actions implicitly update ANY relevant potential task would probably end up being a more complicated system that the previously considered XP per action one) of the proposed system?
Something that does concern me though is that based on the currently suggested objectives, I'm not totally convinced that the proposed system works equally well across playstyles. For example, it's sounds like it'll be great for crafting. Do all the tasks = craft all the things. It'll give you a good tutorial about crafting and is more or less how you would play anyway. But with mining, that sounds like you'll only really be rewarded for completing things you haven't already done, and not actually for playing the game. For example, I want to build a house with metamorphic rock from Therka. If I'm lucky, there will be a task to mine some of it. But after that, I'm not going to get any more experience for it, irrespective of how much of it I needed to build my house? That seems like it might be more frustrating than beneficial, and make being a miner essentially require you to be a bit of an explorer.
Maybe that's the goal though? If you don't have repeatable, or large bulk-tasks, then there's no such thing as grinding for experience. That truly WOULD be a novelty in an MMO styled game .
Also, Explorer tasks (acutally, all tasks that require visiting X planet) seem to have a minor flaw. Exploring something specific assumes that something specific exists. So 'Go to Solum and find X landmark'. On launch, you can set it up so that each launch planet has one or two, or a handful of objectives, depending on the number of planets. But that means that should you be required to add more servers because Boundless really takes off, or (God forbid) it doesn't and you chose to close a few, you'll have to continually keep the potential objective lists updated. Furthermore, it means you can't provide objectives for privately rented servers, because you can't always guarantee people will maintain the monthly fee?
PS. Sorry if it sounds like I'm just finding faults. I'm still, very excited for when this is ready and gets rolled out to have a play with.