It was okay to close it in the first movie, that way if the film did really bad and didn't get a sequel it could be a nice stand alone feature...obviously we got a sequel for better or worse.
I thought the portal opening was actually more simple than convoluted...like a little too easy.
It does seem a little ridiculous that earth was still pumping so much money into the jaeger program even after ten years...
In the first movie, it was alluded that the kaiju were sent to clear the planet...the terraforming bit is kind of just an add on, but it's pretty much the same thing.
Naaaaah. ID2 has almost no redeeming qualities...
probably for the best
They weren't really shooting at it. The "breach" was nuclear in nature (mentioned by the first film) and since the drones were influenced/built (whatever) by the precursors through Charlie Day, they were obviously able to inform the technology and create the necessary nuclear reaction to create the breach again. Who knows why the precursors couldn't re-open it from their side again...Maybe the damage from exploding GD to them from the last film, left their tech crippled...who knows, that's something that can be expanded upon (NOT LIKELY)
There were also groups of drones in several different locations trying to reopen a breach. It wasn't just the one location.
The breach being closed easily in this film makes sense when you consider what was holding it open. In the first film they had to close the breach from the
Precursors side. Which is why we couldn't blow it up from our side with nukes because the precursors were keeping it open with the tech on their side...giving reason why Gipsy had to go through the portal and detonate. In Uprising, it's the drones keeping it open on
Earth side so it was easy to take out the mechanism that held the breach open.