Roadhog was already balanced, at least if you judge by the fact that he wasn't significantly overused or underused in competitive play before.
His utility comes from his hook combo, which would let him basically instakill non-tanks he caught with a hook. With the rest of his kit, he made a fairly good roaming hero, able to travel out on his own safely and sneak a pick or two before a teamfight, since he could win a 1v1 against pretty much any other hero.
The change makes his combo essentially unable to kill targets on its own with any degree of reliability, so your only safety in using it comes from pulling targets into the rest of your team and having them focus. If the dropped the cooldown on hook, it might make him plausibly a CC, but outside of the hook his only good point is as a shield buster.
In a very real sense the nerf turns Hog from a scary roamer who can control flanking spaces just by being present into a bulkier, shittier Reaper.