You should not have this reaction as you do not know how it is currently being fully implemented. Meaning, youre having a strong emotional response to something thats not even in the game yet.
Again, you do not know that it would not be possible to effectively balance. If the goal of BLM is to learn monster skills, then gimping those skills so they "fit" within the current games construct seems silly. Part of the allure of BLM is having skills that are directly from monsters (like Bad Breath). If you were to take that and dumb it down so it could fit within the constructs of the wider game, the skill would probably become moot due to the fact its a CC ability. Given the nature of BLM, its more than likely many skills would fall into that category. That they would be to strong by design, or by numbers.
And because of that factor, that would mean a few things. You would have to re balance the game around BLM (and likely make it a must take on any raid/EX/Etc), or you would have to dumb it down and gimp it so hard that it loses its identity and just becomes purely aesthetics of the skills and nothing more.
This is purely wrong. What is the point of Fisherman in the game currently? It offers little to nothing in the sense of an MMO currently. What is the point of Chocobo racing, or being able to solo things like HoH/PotD. There is a lot of Solo content in FFXIV already, and people do play and enjoy it. So yes, you can have solo play in an MMO, which is what this is. Its Solo play with some party/MMO elements. The Raid community, btw, isnt the entire community. Theyre not the only driving force of the game. Not every bit of content that gets introduced to the game has to be in service of the Raid crowd.
Furthermore, how do you know that therye not working on job rebalances. Far as I know, we know nothing about how job balance will be handled in 5.0. Chances are high there will be some reworkings. Just because they did not announce it here does not mean it isnt happening. There is likely a lot of things that they didnt talk about in the first Fan Fest.
Lastly, people do want more content. And t hat is exactly something SE is giving them. MORE CONTENT. Its not in the usual vein of the game, but it is something to fill down time with. This is why it has a cap, and why it will slowly increase over time. They do not want you to "main" BLM. They want you to have something between tiers that you can play. This is also why NewGame+ exists. To give you things to do when things slow down. Because yes, there are actually a lot of players who wnat to do Solo content in FFXIV. They want to log into the world and just do things without having to interact with others. Sometimes, it's fun not to need a party to do things and still have a good experience in an MMO. And there is nothing wrong with that.
The precedence is only dangerous if it poses a problem to your view on how the game should be. Again, your view seems to be centered around the concept that everything needs to work either in service of Raid, or atleast in service of multiplayer. If it doesnt, its not worth while and shouldnt be implemented. That way of thinking would make this game far more barren and much more uninteresting. We do not know how this is going to play out. We dont. And speculating that this new system is going to be a huge disaster because it doesnt fit your perception of how MMOs should operate is silly. This could be a great thing thatll give us players MORE stuff to do in game, and you are arguing to scrap it before it even is in the game. Good job saying "If it doesnt work the way I want it, then no one should have it."
Not everything SE implements works. We all know this. But Id rather they try and implement new things and fail, then have them stay within the margins. We wont get fun, new, and interesting things in the game if they listen to nonsense like this.