It's a little late, but let me put my 2 cents into this debate..
First, some background on myself. I'm 29, and have been playing fighting games since I was 10, with SF2 in the arcade (my dad would make sure the older players gave me my turn). I started out competitively with Tekken Tag. In Tag's heyday, some of the players in my area (the SF Bay area) decided that it would be cool to run Melee tournaments. Wanting to focus on Tekken, I didn't join them, but it was easy to appreciate what they were doing. For years I watched Melee grow into an interesting and fun competitive game. Then one day, I decided it would be great if I could run and host some Melee tournaments myself. Many players at the time still played in the arcade, so I decided why not bring some consoles into the arcade? It ended up working pretty well. Since then, while I'm still a competitive Tekken player at heart, I've played other games in tournament like CvS2 and ST. I've run over 100 tournaments in various fighting games and so have a lot of experience. Currently, I run Brawl weeklies at the public library where I work.
Now that you know a little about me, I'll get to what I think.
The main difference between the two groups is one of age. The traditional fighting game community is older, generally about 10-15 years older. With the success of SF4 and MVC3, the ratio of older to younger has been skewed significantly, but it is still the older players who run and organize most tournaments. Many of these players now even work for the companies who make the games. Capcom and Namco, for example, have hired many from the community and actively listen to their suggestions. Lead designers like Harada (Tekken) and Ono (SF4) attend the big tournaments in the US on a regular basis to see how their game is being played. Obviously, all this is very different from the way things are in the Smash community. This is why IMO, many SF players call the smash community "immature" or refer to Brawl and Melee as "kiddie games" (to be clear, I don't share in that assertion).
Age in many cases leads to contrasting ideologies. It's this ideological difference that causes IMO the two following other problems.
1)
The Smash Back Room. The traditional fighting game community is run by an older, core group of players that's been around the scene for a long time. The Smash Back Room is run by an older, core group of players that's been around the scene for a long time; basically the same thing. BUT (and this is a big but), SBR makes it apparent to everyone that they're an exclusive, secretive group that runs things. And this is what rubs traditional fighting game players the wrong way. The way things are run is very similar to the SF scene, but the very nature of SBR reeks of arrogance and a bourgeoisie mentality. Why not just take conversations to PMs, IMs, email, etc.?
2)
Items Off/On. The eternal debate. Melee's reason for turning off items was the random exploding containers. Brawls reason is..? Look at it this way, in traditional fighting game tournaments, nothing is banned until a reason is shown that it is broken. Items were banned from Melee for a legitimate reason. In Brawl there was no reason other than preference and people being used to no items in Melee. There's no proof for items "off" in Brawl, just bias and conjecture.
To be honest, I don't expect anything to change at this point. Both groups are quite set in their ways and are very comfortable. When Smash Bros 4 comes out though, things will be different. At Evo this year, MvC3 had over 1500 entrants. I could see even higher turnout for Smash Bros 4 if everyone can overcome their differences. I for one, would love to see Sakurai attend a major like Evo or Genesis. And with the support of other fighting game developers why wouldn't he? Think about it.
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)