The OP is asking for something that ALL MMOs should have, without even questioning it.

Most people are going to decide in the free trial whether or not they want to play XIV, and before someone starts in with "Well, if they're going to be THAT impatient...", please don't.

First of all, there's no such thing as "impatient money" that's somehow worth less than YOUR monthly sub. They take everyone's money and put it into developing more content for the game, regardless of who it comes from.

Second of all, when it comes to low level gameplay vs. high level gameplay, FFXIV's may as well not even be the same game.

With the low level gameplay being as sluggish and bland as it is, it's impossible to imagine how intense it actually becomes at higher levels (usually from level 40+). I've recently brought a few friends into XIV and I've gone to great lengths to assure them that, while combat is fairly "blah" at lower levels, it picks up substantially later on.

If you could have a one-boss trial in which you could take any max level class and try fighting one boss (or healing NPCs as they fight a boss), it would not only give players a solid idea of what they can expect from a class at endgame but also show players just how intense XIV's combat can get at endgame which is something that most wouldn't guess from playing the first few dungeons.

XIV boasts an endgame which is every bit as robust and challenging as that of any other MMO I've played, but it sits behind a leveling process which serves as a very long tutorial that generally offers little in the way of challenge.