If everyone would take a set back and look at this for a minute (and think critically).. It makes perfect sense..
It only makes sense because you're going on Skyrim's system alone and forgetting the things they took out, part of which are the problem with magic not scaling properly to the highest levels of gameplay. It's like they forgot they needed to make up for those systems no longer being prevent, because that is half the issue - there's nothing that can improve spell damage beyond the bought/found/earned spells. No caster stats, no spell making no nothing that can allow for 'some brand' of scaling.
Do I think Destruction should scale a bit with character level? Yes, as the primary source of direct damage to enemies sure.. But people can't honestly expect to just just max every perk in the Destruction tree and expect to be some uber-deathdealing Juggernaut of spell-casting... In fact, I think that, were you to specialize in any particular tree and use it by itself, Destruction would be the most powerful, with maybe archery as a 2nd.
Then you aren't very well versed in the mechanics of the game. Destructions spells beyond the perks and master spells - do not scale. At all. Melee and Ranged both continue to scaled all the way up to 70. You can max out of your destruction spells and get your master spells well, well - WELL - before that in your 30s and even before if you're truly single minded. Let's round and say that's 40 levels where everything else continues to scale, the content around you and, of course, melee and ranged continue to scale all the way 70. Magic though? It doesn't. Certain schools, like Conjuration get around it, but destruction? No. It just stops. It's not more powerful than anything. It might seem like it in the early game but that's stops. And I mean it stops. It doesn't just slowly become less useful. I mean it stops. It never gets better beyond a particular point. It stops. Entirely. No advancement whatsoever beyond a certain point while most things continue right on up to 70, including the content you have to tackle.
You get to the point where a single melee strike can equate to half a dozen casts of your strongest spell, and it gets WORSE because the melee will continue to scale all the way up to 70 so that damage difference only grows larger and larger and larger and it doesn't stop growing larger until you hit the level cap . . . oh, wait, I forgot, enchanting and smithing further the difference even more on top of the base scaling.