In the end, Vince brought more to the table than he took away.
Yes, the territories were the BEST training grounds, for performers and announcers/mangers/valets/etc. They were personal, didn't have to worry about keeping creative support for 30+ performers, and they weren't as shackled by network television companies as modern national companies are.
We have territories now, they are called the indys. Yes, most of it is "garbage" hardcore style "wrestling" (XPW, CZW, etc...), but it is what it is (and there are good places out there, like ROH & PWG). If by territories you mean that there no longer is a national product and that all promotions run in their respective areas only, I regret to inform you that you will be waiting a long time. There is quite simply not enough money and not enough of an audience in most places to justify restrictive territories.
You are right that the death of the territories changed the business, but I do not feel it was the death of wrestling. Whether one likes "rock n' roll" wrestling or not, it simply can not be denied that without Vince's "monopoly mindset" (btw, what was Jim Crockett doing with his company during this time?), most of us on these forums, and in truth most of us watching today, would not be here. We would have never seen anything as well produced (quality, not content) as WCW and WWE. And while many of you may wish for a more exclusive and authentic style of wrestling, it would have made for an industry even more ostracized than it is now in the general public's eye, making it even less appetizing to investors and to would-be performers.
Bringing this back to Vince; if he hadn't taken the WWWF national, someone else would have. Vince followed his vision before the rest of the owners did, but even as far back as then there were power players and politicians in the NWA hoping to take charge of the ship and make a buck along the way. Everyone wanted their promotion to eventually be the better one in the end, and Vince was only guilty of doing it the right (read: profitable) way. It was a shoddy, rickety system that was trumped by evolution.
I do have some issues with the original post, as while half of it is a valid question, the other half is unsupported lies and slander on viewers not in line with your tastes. Let me explain:
If you say: "McMahon ruined wrestling by going national", you are opening up for a possibly great debate/conversation/forum post on his impact on the industry and how it does things. Even if it's based on opinion it's still "fair" because it's a statement that doesn't try to assume my opinions and doesn't try to insult me for them.
And you have WWE marks or whatever you call them that only watch WWE and nobody esle cause they pro WWE and all that nonsense
When you say this, you are sounding like a child and not someone most would want to take seriously. And you aren't really making any sense. In wrestling, reading, video games, and really just anything in life that requires a bit of my time or my money, I am going to go with the product that I enjoy most. Am I a "WWE Mark" and "pro WWE" because I watch Raw more often than ROH or TNA, and because I might once in awhile purchase a WWE PPV but I've never bought a TNA PPV? No, I'm just picky about where I spend my time and money. If I felt TNA delivered a better product, I would be watching them. I agree that it's unfortunate that many viewers will only pick one brand and will never give other promotions a proper chance to impress them. But I don't feel that it's fair to blast them as problems isolated only to WWE. I have a close friend who never gave WWE a chance, and once WCW closed down he never watched a show again. Unfortunate, but I can't force him to like something if he really doesn't want to give it a shot. And it wouldn't be right to.
AND finally (I swear), while I'm not opposed to criticism of McMahon (or really anyone), what I don't have patience for is outright lying and incorrect characterization.
McMahon never had a monopoly in mind. He never bought out companies (minus WCW and ECW), he never "forced companies closed". If anything, he wanted NOTHING to do with as much of the old system as possible. His vision wasn't "take over", it was to separate the WWE from what was around it and make it something new (for better or for worse is for people like us to debate until the end of days). If you want a company that outrightly tried to close other companies, sought to wreck other promotions, and had always stated it wanted to take over wrestling forever, look at WCW under Eric Bischoff. Hate McMahon if you want, from I what I read and hear about him he sounds like a dick. But at least be respectful enough to know what you are talking about.