I don't want to sound like a broken record repeating the same stuff over and over but their are reason's why we need to have multiple ways of leveling for the short and long term for ARR. But first lets always remember and be honest with ourselves is that "a grind is a grind" no matter how you look at it, point simple. We all can agree on the main reason behind grinding for exp is to get to end game correct? Lets continue now with the reason's to having many ways of leveling up.
Solo quest: this allows new players to get started in the game, getting some gear and gil along with some exposure to the world, learning about mob aggro etc & solo tactics. (pro- new players can get a fair start to the game without heavy resistance to progress forward. Con-continuous use will lead them to little or no party play mechanic ability, & cause the community to be closed off as if it were a single player game)
Leves: this promotes new players to team up in duo's/trio's and work together for a common small goal even though this content doesn't require the teamwork and understanding to party play and mechanics of a group. (healer,tank,support,dd, etc etc) (pro-It allows new players to realize its better & easier to team up and have numbers then rather being/trying to solo. Con- continuous use will cause new players to be in a group for numbers only & not knowing any party mechanics)
FATE: (this is speculation given we don't have much accurate info on this, might be similar to XI campaign) newer players individually play buy themselves but work together with random's to achieve the goal of wining. Which this supports Pick up Group's and in general ppl willingness to help each other without reward or praise. Also teaches ppl to fulfill a role that would normally be in parties and makes ppl learn common sense and the ability to do tasks/actions without being told to do so. (pro- new players are more open to help each other and know the basic design behind class/job and have instinct when to use needed abilities Con- continuous use new players get too comfortable playing by themselves while still helping each other a bit but fail to realize a full team effort is key to wining and party success)
Dungeons: This allows newer players to get the hang of party play with a small group (4ppl) to teach teamwork and the beginners understanding behind party game play mechanics.(healer, tank, DD) (pro- new players learn & understand the mechanics behind small/basic party play Con- continuous use new players only know the basics to play party and not the entire works of it)
Mob grind Parties: This promote's newer players to be in a full party further building teamwork and gaining knowledge behind party game play mechanics. (healer, tank, DD, support, Debuff, Puller, etc) Newer players thus learn each role that's needed in a party and learn tactics & strategy. (pro- players learn the entire works of full party play and all the needed roles Con- new players that don't understand the full party mechanics, or aren't geared for it, or not skilled enough puts too much against them to getting started or continue playing especially early on)
Now we can see from the stand point a new player that all those types of content is needed for leveling not just simply allow the player to get to end game content but more importantly make them prepared and have learned the game play mechanics from beginning to end. For any new player only having one of those as a main source in leveling is terrible, you can see from having of all those a new player can grow into and become experienced person. In the new players point if having mob grind parties as the main source we can see the good and bad, same goes for solo quest, leves, dungeons, FATE, etc etc. SE task is to get many ppl playing this game, they already know how to get FF fan-boys/girls back its the new guys they are trying to get and SE knows that throwing a whole bunch of walls and roadblocks at the start or beginning will only deter new ppl from coming in.
As experienced players it really doesn't matter to us which SE will use since for the most part we are skilled and know the game play so its just a grind no matter how we look at it. The only thing we want is either personal preference in one type of grind or we just want a variety of types of grinds because we all know each one becomes boring to do.
Now the experienced players also know that their are more pro's & con's to each level grind type that i stated but for us experienced players leveling up is just something we have to get through just like the new players but for them its more then getting through it, its about learning in the process along with having some variety since everyone learns at different speeds.