Deferring to the OED, Fowler’s* tells us not
To spell “inure” as “enure” for variant
Spellings are not needed; even if “inure”
Has two meanings, it is still only one word.
But who ever heard of “inure” relating to
Anything but some form of suffering?

Something quite beautiful and useful
Might well be put “in ure,” which just
Means we like this well enough to
Make a habit of it, and that cheers
Me up a little, as I had become inured
To “drudgery and distress” (Fowler’s
Example) and need reasons for joy.

You are thinking the primary usage
Became the primary usage because
The world has more misery than
Benefit, but maybe it is the other way
Around. Maybe language defines
Reality after all. If we had inured
All the good things all along,
Maybe we’d be in a better place.

If contemplating stuffy usage guides
Had inured, perhaps I wouldn’t have
Missed so many opportunities to be
Cheerful, to glide blissfully through
A life of Best Practices. Instead, I grew
Inured to heartbreak and dreary poets
Clamoring on about their lost loves.

*Fowler’s Modern English Usage, by H. W. Fowler, a handbook for pedants and arrogant copywriters.