I Don't ever really remember matt hardy being given a legit chance in the main event. unless you're talking about ECW which idk why anyone would consider that the main event. then in almost any feud he had they booked him to lose or after the feud they didn't follow up.
Matt hardy as a face is pretty bland but with that said the face version is one of the most over guys in wrestling. i thought the heel version of him in the feud with jeff was great but after there feud he got drafted to raw and him,regal and chavo became vickies bitches.
I'm sure if given a character or if WWE let him come up with something matt hardy would have worked hard on it and done a good job.
Punk and Swagger were given ECW before they were given legit runs on WWE. Hell even Big Show and Kane have passed through there, Sheamus too even though he never one the belt. I don't buy the "ECW doesn't count" argument because it's clearly worked for a lot of guys with work ethics who's made the most of it. If what you're saying applies to Hardy's attitude then it sounds like he scoffed at ECW instead of using it as an opportunity.
If you have a job and you see people get promoted ahead of you when you think you deserve it, you can be a little bitch and whine about it or you can work hard to overcome your troubles. Hardy chose route number one. The difference? WWE is a public company that makes its money through basically PR, and Matt Hardy was bad PR. It's fine if he didn't want to work there anymore, but instead of going through the proper channels and asking for his release, he decided to act like an idiot and get himself fired by acting crazy and bashing the company publicly.
It's one thing not to be pushed, but Hardy made it sound like WWE was treating him like crap. He was paid, he got to travel all across the world and perform in front of all sorts of people, but god knows if he's not the world champion he's being mistreated... please. There are MILLIONS of people who would KILL to be in Matt Hardy's position when he was in WWE.