Flying around to other planets and investigating other biospheres and their inhabitants is something NASA would do today in the year 2008 AD if they could. I would hate to think in the year 500,000,000 AD that we'd still be doing the same thing!
This is why I don't think any beings that visit us are all that much advanced than us.
But really, why not? Perhaps we're being visited by kids learning basic science in the field. When I was 18 there was nothing much that needed to be learned about clover and rabbit droppings, but we were sent to the Wairarapa to study clover and rabbit droppings nevertheless.
And what if we're
not dealing with an all-powerful, godlike race whose civilisations spans multiple star systems?
What if they are refugees who fled the ruin of their home world using the best technology they had, and arrived here after decades, centuries or millennia in interstellar space, with a population reduced in numbers by the journey and possibly damaged by exposure to radiation (and no I don't think we could be any help with any reproductive problems they might have, any more than a mushroom could), with little or no remaining knowledge of how to survive on a planetary surface or even originally the finer points of operating craft within a thick atmosphere (there's an explanation for you for the alleged early crashes). They would have a lot to learn, and might well be desperately vulnerable if we became aware of them and chose to get nasty.
If there's anything to the abductions, perhaps they're a con-job precisely to persuade us that the aliens are infinitely superior to us in knowledge and capabilities (So You'd Better Not Mess With Us).
If that's true they'd need to hide (bases among the moons of the outer planets, with forward outposts under the seas?).
And for those who enjoy a little Christmas paranoia, it logically follows that they'd be really,
really interested in the real estate. Suddenly I'm feeling a bit David Vincenty...