I glazed over most of this thread, but I felt like I'd add my two cents in.
I've played as Ness in both the 64 version and the Melee version, and I adored the Earthbound game. That being said though, Lucas is a fine replacement. Lucas was very fleshed out in Mother 3, he has some solid looking attacks with those fancy hexagons, and PK Freeze > PK Flash.
Oh, and his hair is of course wicked awesome.
Plus the rope snake makes getting back a much less cumbersome task as it was with Ness, who had to rely solely on his PK Thunder. Which while fun, was still mildly tedious from time to time.
However, the role of Ness in Earthbound, along with pretty much any silent protagonist, should never be downplayed.
Ness' character development is linked directly to the person playing as him. The player gets to include his favorite food, his favorite thing to do, etc., in order to make him feel as though Ness is his representation in the EarthBound universe.
If Ness was to emote constantly and say things, that would take away from the personality given to him subconsciously by the player.
If Ness did something that the player would not do, then that sense of 'Role-playing' is taken away.
As is the basic case with nearly all silent protagonists.
I would list a whole bunch off, but I'm sure you all know plenty of them already.
Without the silent protagonists, Brawl would probably have quite a few less heroes.
In anycase, I understand the move from Ness to Lucas.
Like I mentioned, Lucas is great, and his character has depth that people can relate to. Plus again, who doesn't love his hair? I mean honestly?
The point here is really the fact that Lucas basically has everything Ness had (I'm still hoping he gets the baseball bat xD ), and the wording that Sakurai uses basically sums it up.
We will miss you Ness, but Lucas will take care of your spot with MOTHER pride. <3