If it was a good side board card, wouldn't it be the same when you main deck it? The point of using
Solemn Judgment in a deck is to keep everything in control. You want to go 1-1 as much as possible and create an opening for a 2 for 1 with cards such as
Heavy Storm,
Dark Hole,
Torrential Tribute. Destroying monsters by battle is also a way to gain the upper hand in terms of overall card count.
Then, when you have field control, you have a higher chance at victory when you set that
Solemn Judgment to negate whatever last resort the opponent may have. There is no more
Pot of Greed to allow for 2 more cards to worry about. There are, however, a plethora of draw monsters that may maintain the 1-1
Exchanges, and others that ruin it. The greatest threats being
Morphing Jar and
Cyber Jar. However, aside from them, once you have the upper hand,
Solemn Judgment is primarily used to seal the deal.
Of course, now that many many people have begun to use
Cyber Dragon Aggro decks, why not combine YOUR aggro with
Solemn Judgment? Overpower their monsters and negate any big threats.
There will always be downfalls to using cards. You've mentioned 2, and I add the opponent's
Injection Fairy Lily,
Kinetic Soldier, and Burn decks to that list. The biggest threat in the previous format was
Ring of Destruction. Even with 3
Book of Moons, there was always a game or 2 where you could not stop the burn.
I am not saying splash 3
Solemn Judgments into any deck. What I am saying is that 3 in a deck that can control the board will greatly enhance its effectiveness. Besides, wasn't that the purpose of siding it in before?