1- What's your opinion about this? (Summarize)
I would have preferred a free solution. The space they provide us with by default is nowhere near sufficient if you (as the Game supports) play many roles. So first they create a system that invites you to try out different things, then you get insufficient storage space and in the end, they come up with "if you want more, pay". We talk about pixels here, more of something that exists already so no hard work is needed from DEV side to provide us with one more of the same. If they must charge us to compensate for server space or whatever is needed, I would have preferred a one time fee instad of a monthly fee. But all in all it is no biggie. It is nothing mandatory, Joe Average (1 fighting class and done) won't need it and it is your personal option so you have the choice.
2- Do you think we will have more things like this in the future totally changing our idea of FFXIV:ARR?
Once they start with such a path and receive enough interest, they will continue so Yes, I am almost sure there will be more paid "services" like that.
3- Am I just exaggerating and it's something normal or that, 'doesn't affect gameplay' even if it's confirmed that those 'ventures' will grant us items, and even if it is clear that we will need more space storage in the future?...
Naturally this isn't normal at all for me but sadly a normal industry standard these days. Constant cash flow is the keyword for managers and CEO's. If you can't generate continous revenue, you won't get budget. Developping and selling a Game only is 20th century. 21st century is develop a litte, make people pay, develop a little more and make people pay again. Repeat till people have enough and go for the next big thing.
4- Is our voice enough for change these things?
I seriously doubt it. Only chance we could have would be that only a very small number of players use services like that. But I know I will use it because I do not have enough space and I am sure many others will suck it up and pay as well so success is more than likely no matter what people really think of it or have to say about it.
5- Should retainers be in-game for guil or any other ways, giving the currency a little more of importance aside of housing?
In Game for GIL should be the way
6- Taking in mind these kind of strategies, do you think eventually the game will become a Pay 2 Win, or, not radically that, but, slowly increase the amount of money we pay per month if we want to play it full advantages?
At the moment, I do not see a P2W element just because of the retainers. They can be a reason that you may have more GIL than others if you order a lot of them and send them steadily out to gather materials but the way this Game is designed, only drops from dungeons or items you buy for tokens or a currency like Myth tomes really count.