I think they changed it simply because they thought that’s what players wanted when people on the forums were clamoring for more buildable locations.
It’s been pointed out to FC that the maelstrom is still not really attractive for building because it appeals to neither PvP players (no defensible locations) nor PvE players (hardly any visually striking locations).
That’s why I never really understood any of the screeching about the maelstrom being unbuildable. Why would people want to?
I wanted to because I thought it would be fun to build a base that could defend itself from the storm, but even on my private server with maelstrom damage off, that wasn’t really possible because the elder siege things weren’t implemented in a way that made that feasible. Namely, they spawn inside your base.
For the same reason people were screeching about any other differences between Exiled Lands and Siptah: people didn’t want Siptah, they wanted bigger Exiled Lands.
Personally, I liked Siptah being different, and I thought it needed to be tweaked rather than reimagined, but I was clearly in the minority and that’s that 
I am certainly not a fan of the Thrall Slot Machine system. Paying for Thralls to fall out of the sky… I still haven’t done it yet as it is so unappealing to me. I’m enjoying the purges and raiding villages. Was not a fan of cage rescues at first, but now I really enjoy it - ever since finding a T4 bearer in one. I gleefully slay jailors every chance I get. I still have a couple I captured before the patch, but I’ll turn them loose soon, since they aren’t intended to be thralls.
Maelstrom is fantastic. Best part of the game so far. It just needs some precise tuning to keep it challenging. I have a team of 10-12 T4 fighters with a variety of weapons, to make sure we hit sunder, bleed, poison and cripple. Lots of pikes for the reach, since they get crowded. All dressed in T4 armor and eating for buffs. It is exciting and vastly more rewarding than the other aspects of the game right now.
I have some ideas that can help change the storm into something that works for everyone, rather than an on or off by server situation. More on Suggestions forum…