I'm very new to the forums but I signed up to give my voice on this.
I know this is a very divisive issue, and that there are two groups: the people who want a "real, true, learning BLU" and the people who want to have BLU as their main job.

I am very upset that I can't currently play as Blue Mage in all content, as I have wanted it to be my main job for years. But honestly I don't think those two sides need to be apart.

Yoshi-P has always been an advocate for content for all kinds of players. Remember his reply to the open world PVP question at NA Fanfest this year? The audience member asked if any open world PVP was planned. Yoshi said no, but responded negatively to the applause that followed, stating that while it's fine to wish for content you like, it's not cool to wish that others do not get content they like. I really respect that attitude, but I also think it can be applied to the Blue Mage.

Instead of implementing a very popular, very nostalgic Job with only one real form of content, it would be more appropriate to include both fun solo content and the ability to raid as a Blue Mage. You could integrate the spell learning aspect heavily into the leveling process while keeping the benefits of balanced high-end play.
There are all sorts of proposals on how to do this, and I might even post a few of my own ideas in the coming days.

I have faith that the company who made the best RPG franchise ever, and who turned FFXIV 1.0 into the best MMORPG on the market, can turn this mistake into a miracle, and I look forward to seeing future developments.