On Learning Blue Magic
Many people, Yoshida included, have a tendency to overthink the learning process. When people think about learning Blue Magic, they imagine venturing out into the open world, exploring a specific area until a specific monster is found, challenging that monster, then biding time until the desired ability is used against the Blue Mage, ending with a randomized or guaranteed chance of acquiring said ability.

In reality, that isn't how it's going to work. For starters, Red Mage and Samurai set a precedent. There is a high probability that future jobs will start at level 50 with all spells and abilities between levels 1 and 50 already mastered. Right from the start, Blue Mage will have all spells up to level 50 without putting forth an ounce of effort. Does that take away from the experience? Yeah, I think so, but it at least 'addresses' the issue of how Blue Mage will keep up with jobs that learn actions by leveling up by bypassing the entire process.

Moving forward from level 50, that is when it becomes a requirement for jobs to complete quests to learn new actions. This is the environment in which Blue Mage will learn new spells. It also doesn't have to be as basic as, "go into that field and fight that enemy until you learn something." Imagine if the main antagonist of the Blue Mage quest-line was a Beastmaster who tames monsters and pits them against the Warrior of Light, resulting in the Blue Mage becoming stronger as he or she overcomes the monster threats.

Now there are some cases past level 50 in which jobs learn new actions merely by leveling up. Specifically, in the level 60 to level 70 range. However, I don't think it would be unreasonable to ask Blue Mage to continue completing quests to learn new spells.
The Role of Blue Mage
There is a widespread belief that Blue Mage was always an incredibly diverse job that could fulfill the functions of any role, or at least mirrored Red Mage in terms of functionality. This, however, isn't entirely accurate.

Looking back at FFV, there were thirty Blue Magic spells. Of those spells, there were only four that didn't either inflict damage or inflict a negative status effect on an enemy. Those four spells were Moon Flute, Transfusion, Mighty Guard, and White Wind. Those first two were also double-edge swords, with Moon Flute inflicting Berserk on the entire party, resulting in a loss of control over the party's actions, and Transfusion which fully restored a party member's HP and MP, but by sacrificing the Blue Mage.

Throughout the history of Blue Mage, there were occasional unique utility spells. Blue Mage even had access to raise in one or two instances. However, the only defensive or support spells that have been present in several instances have been Mighty Guard and White Wind. And in all cases, the vast majority of Blue Magic have focused on either dealing damage of inflicting negative status effects.

My interpretation is the Blue Mage should function as a (support) DPS with Mighty Guard and White Wind as its unique raid utility. Nevermind the fact that Mighty Guard is currently a tank Limit Break. They can always change the name.