Was America's entrance into WWI justified?

[Free Palestine]

No.  Had we remained completely neutral (no aid to the Entente) there would be no Lusitania, no Zimmerman Telegram, and more importantly, no Hitler or World War II (as we know it).  The outcome of World War I led directly to World War II.  It's interesting, it's like a historical domino-effect.  World War I led to World War II, which led to the Cold War, Korea, Vietnam, and eventually Iraq and Afghanistan.  And what caused this all was our intervention.

[Free Palestine]

Wait a sec.  You talk about how the Central Powers were abhorrent regimes, then you call on us to get into the war to save Tsarist Russia?

Not Tsarist Russia; save Russia from Bolshevism.  We could have helped stabilize and maintain a more democratic regime; given Kerensky time to create a new, more liberal Russia.

Or we could, you know, not dick around with the sovereignty of other countries.  The Russian Revolution was an internal matter, and we had absolutely no pauldamn right to interfere either way.  Saving Russia from Bolshevism is not a valid reason to expend huge amounts of our money, as well as thousands of American lives.  America is not the sovereign of the world.

[Free Palestine]

The Central Powers were for the most part morally abhorrent regimes; at least Britain and France were liberal democracies, something none of the Central Powers can claim.

Germany was a democracy at the time.  Had more liberal voting laws than Britain.

This.  The Ottoman Empire had a parliament, as well.

[Free Palestine]

I somehow doubt that being a democracy really makes you "the good guys."

[Free Palestine]

This.  The Ottoman Empire had a parliament, as well.

That means nothing.  They were a repressive, bigoted regime.

As were most other participants in the Great War.