I wouldn’t call myself a casual player, but from my point of view, Final Fantasy 14 used to have good content for casuals, but lately, they’re no longer focusing on bringing that same level of quality. For me, a casual player is someone who invests little to no time in improving at the game and is content with staying at a "normal" level and that’s absolutely fine. So, for me, content like Palace of the Dead in a group feels like casual content until the last floors, as it’s similar to dungeons with some mechanics that can kill you.
Eureka was content that not many people liked because of the experience loss from death. Bozja, part 1, was hard at the beginning, but it became easier as you progressed, which I really liked. The thing is, someone who isn't interested in constantly fighting for their life will try this content for a while, then drop it. In my opinion, casual content is something that can be done without feeling like your life is always on the line. Yes, I know people will say, "Stop making the game simple," but that’s what the game is. What keeps the game alive are players hunting for glamour or housing items period.
Unfortunately, Final Fantasy 14 hasn’t offered much in that department lately. Why not evolve and make the overworld more useful instead of having maps that people never visit again? We have FATEs with some rewards if you do something like 5,000 FATEs for one mount, but let’s be honest who’s doing 5,000 FATEs? It’s Final Fantasy add treasures in areas we don’t usually go to, or random events. Give people something to do instead of standing AFK in Limsa or in their houses.
Dawntrail should feel like a vacation where we’re adventurers again, so why not give us more to explore? Make achievement points more useful by adding more rewards, or create special content for jobs so people actively want to try different ones, instead of just saying, “I leveled everything.” I think when a typical casual hears the words "EX" or "Savage," they just tune out because that content isn’t for them.
Variant dungeons were great for casuals, even though some found them a bit hard. You had a manageable dungeon with different paths to take and a mount as a reward. Stuff like that is good casual content, in my opinion. Other things to consider are QoL updates, making the game more alt-friendly, and having events that are bigger than just two quests where you skip the cutscene for a hat.
Involve older expansions if you want like Blizzard did with the Pandaria remix. I don’t know, but sitting on the idea that we just need more raiding content isn’t how casual players will be satisfied. The key is figuring out how to implement content that pleases all sides. Answering that is no easy task! ( the announced housing stuff is very great but you need a House first which is savage content)