Originally Posted by pr0xyt0xin
After what, 5000 years? The convergence awakens the Aether and it is the source for these blurred borderlines of the realms. It may have been hidden REAAAAALLY really well but it is, in itself the source of this reality warping. Thusly, Earth is not the center of the situation, The Aether is. And being the one focal point blurring the lines between the other realms, one of which is Midgard. Another of which (if you remember) was Asgard, when Loki's little portal pops them out walking distance to the Aether's hiding place as well?
Still. Not really seeing any particular cinematic catastophy of a "convenience"
Lets look at some other conveniences.
Rhodey fits perfectly into Iron Man MK II?
Loki fell off the bifrost and somehow ended up in Midgard with no explanation.
Captain America being discovered in the ice just months before The Avengers have to gather to defeat Loki's army?
Bifrost is destroyed but Odin can summon dark energy to transport Thor to earth just before The Avengers have to gather to defeat Loki's army.
Iron Man fell through the closing tesseract portal split seconds before it closes. pretty freaking convenient if you ask me.
Yet this one is the one that is the problem?
Whether I agree if those are extreme conveniences or not, none are the only thread tying the entire film together. The one person in the universe that sutbles upon the Aether, at the exact right time is Thor's girlfriend. Everything is written to feed that, to get Jane back to Thor and to Asgard. Cap getting out at that time is convenient. But it doesn't bend the entire plot of the Avengers to it. Same for the rest.
The one thing in the universe the villain needs falls into his lap thanks to Thor's girlfriend. You can be ok with it, that is fine. I don't love it, but I got over it.
By the way, on Thor being sent to Earth in the Avengers. It is to get the Cube and Loki. They are aware of his planes and they know they can use the Cube the travel and fix the Bi-frost. The dark energy is a last resort, one way only thing. That isn't convenient, that is good writing imo.