Is it possible to lower requirements for certain achievements?

I have over 5,5k achievements and don't see any problems with getting the rest naturally over time except some due to ridiculously high requirements which probably make them non-obtainable to me and other people in the game's lifetime.
Triumph in 5,000 matches at the Wolves' Den.
With Woves' Den almost dead queues you're lucky to get a couple of wins per day, and it'll take years to reach 5k wins. I've never seen anyone with The Alpha Wolf title awarded for this achievement.
Earn a cumulative total of 10,000,000 gil from levequests.
It wouldn't be too bad, but GC leves (who have their own set of achievements) award you with zero gil. Battle leves rarely give over 500. To make any significant progress you need to use thousands of leve allowances for triple HQ turn-ins in Mor Dhona, but they are not profitable and require a lot of spare time and money to waste just for this achievement. I've never seen anyone with Honest Gillionaire title awarded for it.

The first one is probably just an incentive to actually get players to participate in PvP, but as you noted, that hasn't actually happened in practice. I don't really see SE making a change to this though, unless they add some other kind of incentive to do the Wolves' Den.

As for the second one, that achievement was actually an achievement from version 1.0, and thus had to compensate for 1.0 players, as any progress they might have made towards that achievement in 1.0 transferred into ARR (you can tell these kinds of achievements by the two stars and arrows on the achievement). So it had to be a deliberately high amount accordingly.