XIV still has a pretty decent level of attention demand at least at higher level content (yes lower level content I've fallen asleep as SCH in copperbell).

Some mechanics are probably simply not practical to do because of the actual class mechanics of the game, though (remember that we have nine DPS jobs and you can only take two to a dungeon, four to a non-alliance raid or trial, and there aren't many CC/interrupt actions; "the meta" is enough of an issue for some jobs as it is without actively making the content call for specific job abilities).

As for length, gamers on average probably have less free reliable time in continuous blocks than before, so the bite sized instancing of XIV is a better idea (consider how PUG raids get in WoW with the long multiboss dungeons, if e.g. savage was a single instance you'd quite likely need to clear O4S to pug savage at all).