Before I get to the meat of the matter, let me say this: I love what the Marvel team is doing with their characters so far.
Jon Favreau, Robert Downey Jr and co have made a superb first stab at Iron Man, with what looks - based on the footage at Comic-Con - like an even stronger sequel.
Louis Leterrier put in a solid, if uninspiring effort with The Incredible Hulk, and I'm excited to see what sort of epic, Shakespearian tone Kenneth Branagh will bring to Thor.
Favreau has said recently that he won't be tackling The Avengers, largely because his schedule is understandably crammed.
He's a man in demand after the success of Tony Stark and co. Even he, however, admits that combining all of the various hero characters is a big challenge:
"It’s going to be hard, because I was so involved in creating the world of Iron Man and Iron Man is very much a tech-based hero, and then with Avengers you’re going to be introducing some supernatural aspects because of Thor.
"How you mix the two of those works very well in the comic books, but it’s going to take a lot of thoughtfulness to make that all work and not blow the reality that we’ve created.”
And it's not just Thor - it's possible The Hulk (who may play the villain) and Captain America to boot.
Taken separately, they're like great flavors that work fine. But blend them together and chances are you'll get a vomit-worthy concoction that melts the glass it gets poured into.
And its not just the feel of the film, it's the directors' various styles.
Will they mesh properly, or will they just feel awkwardly bodged together? I'd guess the latter.
Plus, with zero disrespect to Branagh and Joe Johnston, who is working on Captain America, but what if those films are bad?
What if no one wants to see more of Chris Hemsworth as Thor or whoever they get to play the Cap? What then? Marvel has a release date announcement, a great character and some baggage they don't need.
Yes, I'm quite aware I'm saying this without anyone having so much as written a storyline for The Avengers, and that all the problems could be solved by an amazing script that somehow solves the big issues.
But that's an awfully big "if"...
It's a damn good thing that Marvel is being smart about this and taking its time with the film, since it gives the company's creatives types time to try to figure all that out.
The solution is simple: don't bother. No matter how much you think a certain chunk of the fan base is crying out for it, or how much money you believe you'll make if you release it, it's not worth the risk.
Keep producing good separate movies - and develop other Marvel characters who could more easily slide into a team with Tony Stark.
Hell, you've got Samuel L Jackson under contract for about 73,000 movies, why not a SHIELD film?
Marvel's done great work so far. Don't spoil an amazing run with a big mistake because you feel you need to.
Are you excited for the Avengers? Do you agree it's a Hulk-sized mistake? Tell us below...
More TotalFilm.com blogs;