One of the things I used to typically do every time a new zone came out with the zone meta. It kept me in zones longer. I played them more.
According to GW2 Efficiency, the percentage of people who have completed zone meta achievements are trending down.
Ice Brood Saga
Blood by Blood 4.559%
Whisper in the Dark 9.028%
Shadow in the Ice 2.809%
Steel and Fire 1.326%
No Quarter 1.493%
Jormag Rising 1.293%
I know for me, and I can really only speak for me, I stopped doing zone metas the moment strike missions were required for some of them, and I haven't really gotten back into that mindset. To me, Strike Missions are just content I don't find fun, and have the added stress of either having to find a group or having to endure really bad public groups. This problem doesn't exist as much with meta events, because you're not necessarily interacting with others personally. Most of my guild isn't interested in Strike Missions and I'm not either.
Obviously this is only one person's opinion, which is the only one I can speak too. I guess I"m curious why fewer people are doing meta achievements these days and what would it take to bring them back.
And yeah, I get 4 or 8% of Guild Wars 2 efficiency isn't necessariliy representive of the entire player base, but it is representative of those who have efficiency accounts, so it can show a trend.