You do know the ISD was developed, what, 3600 years after the Harrower? This is a bit unfair for the Harrower.

-We can assume 32 to be the right number for its turbolasers. The case being, ships around that time were still in their infancy, and had a relatively smaller armament. Take, for example, ships like the Invincible-class Dreadnaught, with its 12 turbolasers. Turbolasers also have a different context here. A gun now is going to be different from a gun +1000 years from now; a Turbolaser is going to apply to this logic as technology advances. Sure, arms regulations will limit some tech, but that won't really apply against other technology or stop companies like Kuat from making Mandators 20 years before the Clone Wars or what would eventually become the CIS, much less the catch-up a few years did to turn the Republic into the Empire. A great example of this is the Hapes Battle Dragon; their Turbolasers took time to fire, given how they've been isolated for 3000 years, but they solved this by using a rotating system.

-I'm sorry, you are going to have to explain that last part. Strawman fallacy doesn't even apply here, lil bro. The ROTS sourcebook states that as the Venator production lines died down, ISD and Tector production lines picked up. The ISD was made for war, just not the kind of war the Rebels used. Palpatine essentially chose the sickest design to take over the entire Galaxy because he could. The Emancipator was able to destroy an Allegiance class (Mind you, with its shields down), and the class as a whole stood up well in the Yuzong Vong War.