No, the Goliath’s anti-air attack was very different from the Viking’s. Don’t try to butter things up by making false statements.
As an anti-air unit, all versions of the Goliath are outright superior to the Viking, and considering that the anti-mechanical damage was a later change to make Vikings useful on the ground, it is wrong to assume that Goliaths would not have received a similar bonus.
The original Brood War Goliath’s attack cooldown was about 1.25 (that is 0.89 in SC2 faster units), and it fired two attacks that each dealt 5 (+5 v. armored) with +2 damage on upgrades. That is 8 DPS with 16 DPS against armored compared to the Viking’s 10 DPS and 14 DPS against armored. With upgrades, the Brood War Goliath pulled ahead at 12.8 DPS against non-armored units and 20.8 DPS against armored units.
In practice, this means that the Goliath had 28% to 48.57% more DPS than the Viking at 33% less cost. It outright outperforms the Viking as an anti-air unit.
The scrapped StarCraft II version of the Goliath was ahead by even more. That unit fired two missiles at 8 + 8 v. armored on a 1.5 second cooldown (1.07 seconds on faster) with the same +2 damage per missile.
The SC2 Goliath starts at 10.66 DPS against non-armored air and it has 21.333 DPS against armored air (50% more than the Viking). At +3 upgrades the SC2 Goliath has 14.666 DPS against non-armored air and 25.3333 DPS against armored air.
In both cases, the Goliath ends up beating every air unit that Vikings do and a number of air units that Vikings lose against.
The Viking’s ground attack without the bonus to mech is actually stronger than the original Brood War Goliath’s.
However, the SC2 Goliath’s attack started with the same DPS, and it is fair to assume that it would have received a similar anti-ground change to the Viking.
Goliaths hard-counter Carriers. The only way that Brood War Carriers are able to compete with Goliaths is by abusing terrain to ensure that most of the Goliaths cannot fight back.
Templar are not a good argument against Goliaths. Vikings have the exact same problems against Storms that Goliaths do, and Goliaths would arguably fair better because they cannot clump as tightly and because some iterations of the Goliath actually have more health (about 150).
The Immortal and Disruptor are the cases that would be more problematic. Goliaths are always vulnerable to those units, so they would be much easier to beat from the ground.
There’s also the Tempest case. Vikings have always been very bad at dealing with Tempests because they are a ranged unit that relies on outranging other units and doesn’t have the speed or health to charge forward and kill something safely.
Goliaths would be much better against Tempests simply because the Tempest’s range against ground is much lower.
The Thor’s anti-air DPS is an always has been very low for its supply. Thors simply cannot be balanced with much anti-air DPS when you take their range and supply into account. Thors end up beating Brood Lords only because most of the Brood Lords’ DPS is tied up in its Broodlings and you can kill those immediately with Hellbats.
Individual Goliaths have about the same DPS against air as a Thor, and they can be balanced with that DPS because they are much squishier. If you defend your army with Goliaths, then you can basically kill most air units much faster so that they have less time to attack the rest of your forces.
Basically, Goliaths would be nice to have. It would be nice to have a ground unit in mech that can shoot up without crap DPS (Thor) or a lock-on requirement, but it isn’t necessary because three units currently overlap to deal with all enemy air units.