Blue Orange
Gone to Texas
kiloRaistlin? So destroying 1000 worlds? You probably wanted another SI prefix. 
As one of the previous advocates of the view stated by the OP, I want to say: that's my interpretation. If you decide wizards in your world are like artists and creatively compose spells or like salesmen and talk the universe into doing what they want, go for it. Magic ain't real after all.
I think the reason this trope keeps coming up is (1) wizards are one of the few classes to use INT as their prime requisite...er, chief stat, and in particular every other caster uses WIS or CHA, the exception being the artificer, which is basically a magical engineer (2) the idea of becoming powerful by studying is appealing to the large bookish portion of the game's fanbase (3) most D&D worlds have magic instead of science, so maybe the magic specialists act like science specialists in the real world.
It's also one of the three oldest classes in the game, so it's built up a lot of lore over the years.
I think one of the big things about 'rationality' is that the 'mad wizard' is essentially the fantasy version of the 'mad scientist', a Faustian figure who's a good way to introduce any new element you want to invent. Want a green monster with five arms and three tentacles? Wizard made it. Want a portal to the alternate fantasy world you want to play in for a session? Wizard made it. The cleric has to do what the god wants, the druid has to be pro-nature, and the warlock's only got what their patron dishes out, so if you want to invent something, it's probably a wizard.
Wizards aren't like real scientists...you never see a wizard spending all their time begging for grant funding. (Wizards having to hire themselves out to patrons to get money for their experiments might be a nice way to drive a plot.)

As one of the previous advocates of the view stated by the OP, I want to say: that's my interpretation. If you decide wizards in your world are like artists and creatively compose spells or like salesmen and talk the universe into doing what they want, go for it. Magic ain't real after all.

I think the reason this trope keeps coming up is (1) wizards are one of the few classes to use INT as their prime requisite...er, chief stat, and in particular every other caster uses WIS or CHA, the exception being the artificer, which is basically a magical engineer (2) the idea of becoming powerful by studying is appealing to the large bookish portion of the game's fanbase (3) most D&D worlds have magic instead of science, so maybe the magic specialists act like science specialists in the real world.
It's also one of the three oldest classes in the game, so it's built up a lot of lore over the years.
I think one of the big things about 'rationality' is that the 'mad wizard' is essentially the fantasy version of the 'mad scientist', a Faustian figure who's a good way to introduce any new element you want to invent. Want a green monster with five arms and three tentacles? Wizard made it. Want a portal to the alternate fantasy world you want to play in for a session? Wizard made it. The cleric has to do what the god wants, the druid has to be pro-nature, and the warlock's only got what their patron dishes out, so if you want to invent something, it's probably a wizard.
Wizards aren't like real scientists...you never see a wizard spending all their time begging for grant funding. (Wizards having to hire themselves out to patrons to get money for their experiments might be a nice way to drive a plot.)