Pros and Cons of Making the game Pay-to-Play

If everyone stays and has to pay 5 dollars more than what they're paying now, Nexon would lose money because that's 10 less cubes being bought? Who's to say less cubes will be bought as a result of this? Who's to say they can't make cubing cheaper? There's no correlation between spending habits and a mesely 5 dollar surcharge imo.

Because the Pay to Play charge is bad for pulling players in. It turns a lot of people away. The people it keeps, they are less likely to spend because they're already spending to play in the first place. To top it off, there's no excuse for the Pay to Win scheme they have now if they're going to force a Pay to Play scenario. It's insulting to the players. It's essentially saying,
"Hey, want to play the game? Pay monthly. Oh, you want to actually DO something in the game now? Pay more."

There's a reason the majority of games besides WoW have shifted off of a Pay to Play subscription fee.

Rather than charging a monthly fee, just an outright $5 to create an account would solve at least 50% hacking problems and weed out a good 50% of the population that is mentally retarded. The rest of the game could stay as it is.

This is far better than a Pay to Play situation. It's essentially Buy to Play. But that's not really stopping many hackers in other Buy to Play games. I think it's a good attempt, but I doubt it would really do all that much, at least in terms of botters. Maybe hackers, but that depends on how much money they make off of their hacked gear. It would certainly deter regular hackers, but those in it for profit...another story.

What's the point of paying monthly fee if you still have to pay for stuff?

Not just paying for stuff, but paying for EXACTLY THE SAME stuff.