I think it's sad to pass on a game due to it being the same type of game as XI. XIV is vastly different, even though they used many of the same or similar elements (such as races etc). XI was designed to be played with friends or allies. There was almost nothing you could do in battle without a party, because even the weakest enemies could overwhelm you. That said, I still think XI did what it did to perfection o_o. For the type of game it was, it was always heralded as a good MMO.
XIV however, offers much more freedom. You can do a whole plethora of things from an early stage in the game and you can free roam at ANY time... Meaning, you can travel through the entirety of Eorzea single player without too many issues. Same goes for the battles in the world. It's onlywith stuff like dungeons and instanced raids you have to think about multiplayer. But because these only take a fixed amount of time to finish, you are never left with the feeling that you need to party up to complete something, because it just feels natural that it is how a dungeon works. I'd really recommend giving it a try. There is so much to do and it's easy to level up. It's kinda like playing a single player game where you can co-op whenever YOU want to, just that the world and gameplay elements are on a much larger scale than a single player.