Disintegrate change to spell attack

One of my players (A soc) asked if disintegrate could be changed back to a spell attack.  (In 3.x it was a range touch and in 5.x that would make it a spell attack not a save.)

I am think about letting it as there are not many high level spell attack spells.  I know him being a soc he will be able to get advantage with it.  Also legendary resitances will no longer save you from the spell.  Also as a attack the spell will be able to crit (10d6+40 ave 75 to 20d6+40 crit ave 110.)

Does anyone have any other reason not to change it to a spell attach vs Dex save?

There are several more feats/features that can affect an attack roll.  Negatives include disadvantage if casting within 5' of an enemy, opponents taking advantage of cover or melee combat with allies and others.  I do get the request, I'd rather have the dice than have the DM roll a save every single time.  I built a 3.5 Wizard around the Orb spells (all attack rolls) just to avoid opponent saves.

I’d recommend not changing it to a spell attack since the game design of 5e was not balanced with that in mind. On average, it’s a lot easier to hit with attack rolls than saving rolls due to a monster's ac being lower while a lot of monsters have high dexterity or proficiency in the saving throw.

Since Disintegrate is one of few save for none damage spells, I'd be okay with this. Put things in the player's hands a bit more.