I don't see why there is any backlash against online play. My theory is that the majority of posters here do not have extensive experience with any online games.
To the OP - i have no idea how you decided that neither "party" games nor "fighting" games are intended to be online, that holds just zero credibility.
The fact is that adding ONLINE content does NOT HARM SSBB OFFLINE content. It is what is known as a "nonrivalrous" relationship, just like information. If I possess knowledge that I impart to you, it doesn't mean I lost the information. Just the same, if I play online and you don't, it doesn't take away from your experience.
The two chief concerns espoused by the community that I fail to understand are LAG and COMMUNITY MAINTENANCE. I will also detail a stint on why I believe a leader-board is a good quality for SSBB
First, LAG. Yes, it exists, and anybody that has played an online game in the past decade knows how it can affect gameplay. But Smashers are wrong to believe they are special in regard to lag. Smash will not be the first "twitch" game nor is it even the "twitchiest" game. In fact, in terms of supporting an online fighting community, Smash is a rather good fit.
If you look at games like Counterstrike or Quake, they have two sources of imbalance - speed of the computer and internet connection. That is, raising your FPS increases your advantage in addition to your internet connection.
Smash is different. Played on the Wii, everybody has an equal gaming platform, and the game is locked at a set FPS (60 for SSBM obviously). This removes one source of inequality.
if your argument is that "liek ZOMG - SMASH REQUIRES ISAI-LIGHTNING-MODE REACTIONS AND OTHER GAMES DONT!" you are plain wrong, and have not played another twitch game at a competitive level. Yes, a fraction of a second can mean you get hit, combo'd, perhaps even lose a stock. In CS, a headshot is the end, no questions.
Other games have succeeded tremendously going from console -> online, Halo and Call of Duty come immediately to mind. Smash is not so unique that it can't follow suit.
COMMUNITY
This argument is laughable really. When has putting a game online DECREASED connectivity? The answer is NEVER. You will still play with your friends just as much, you know why? Because they are your friends, and they are FUN! Tournaments will still be held in person, just like every other competitive gaming function (CS, Halo, Quake, Unreal, whatever) because it enforces a level playing field. Again, this is the nonrivalrous aspect - you have your friends, you can play with them. My friends dont play smash, I can play with my online friends. More fun for everybody.
As a community, Smash only stands to gain from going online. If you disagree with this statement, ask yourself why, and objectively analyze your answers credibility. Note Bene: If you are 15 and you answered "because I want to PWNZ my friends on my 17" plasma W()()T" you are the antithesis of these forums and detract from the community. You have no say in arguing the merits of community and online benefits. Bringing people together does just that - brings people together.
LEADER BOARD
This is where SSBB could soar, this is where it could cement its place among competitive console gaming and maintain a HUGE following. No more MLG dropping SSBM like its hot, no more commentary like "Well since Halo isn't starting until tonight, we have time for 6 rounds of this best of 11 match!"
I fear the distribution of ages on this board may be too young to actually admit that some hacker 4 stocking you and climbing the leader board, contrary to popular opinion, DOES NOT harm your experience of the game. adolescents are adolescents, they are cocky, defensive and most of all prideful. that both lends competitiveness to the smash community (good) and rampant immaturity in terms of logic and actions (bad).
By applying economics to satisfaction, we can determine if online play is a good move for the general populous. It's quite simple really, if the BENEFIT of ONLINE > COST + DEMORALIZATION then its good. In this instance, the benefit is the total fun, the cost is the extra price incurred (likely 0), and demoralization represents the amount of people not playing because they are upset by negative facets in the game (hackers). It is clear to me, at least, that the overall benefit FAR outweighs the price of COST + DEMORALIZATION in this case.
The benefits of the leader board are immense. It brings players together that otherwise would never have met each other. Online relationships are real relationships, the player ranked above you could become a quality friend. Furthermore, it acts as that XXXX FINDER on a COMPLETE level - if done regionally, you can discover who plays in your area at the very least.
Most of all, it increases playability. If you dont feel like destroying a lvl 1 cpu and no friends are around, hop on and play a match in your skill bracket (if implemented). Hopefully, you can play against people similar in skill until you develop a record (or ratio more likely) that bumps you up a bracket. Through this, you will continually improve AND HAVE MORE FUN.
I never meant to write my senior thesis on SSBB Online Theory, so I will answer any theoretical questions people have, but I'm done bogging down this street corner