I'm not used to Sindri having the correct take and being surrounded by terrible ones, but here we are. Fitting Blue Mage into the holy trinity paradigm requires stripping it of everything that makes Blue Mage iconic in pursuit of aesthetics alone. If you'd be happier with a regular rotation caster with "spell glamours" that has no discernible mechanical identity, then more power to you, but you like boring things and represent one of the reasons class complexity has gone down over the years.
Then you weren't taking full advantage of them. Any mainline game with an unlimited Blue Magic equivalent usually finds it somewhere near the top of the power rankings. FF5? Trades top spot with Chemist depending on version. FF7? E.Skill is generally considered the best materia. FF9? Quina is outright gamebreaking. X-2? Completely coked out and only really beaten because that game has a plethora of gamebreaking combos. Strago's just about the only mid one.