On Roster/More Characters: I can provide some perspective on this. It’s true they do already have some of the materials to go forward with more characters. However, this is reduced work versus no extra work. Here’s what they have to do when they go that route. Forgive me in advance, this is a little long. (Edited to shorten it slightly)
Art pass: They can’t just use the old Melee or Brawl graphics as-is. At the bare minimum they’ll need to be redone at a higher resolution for the Wii-U. And they can’t just up-res what they already have, going from low to high res introduces a lot of ‘artifacts’ that look terrible. Now if Nintendo was smart, they actually did the original art at very high resolution and scaled down to fit the hardware. If so, that’s most of the work already done but there will still be a lot of touch-up necessary; the ‘skins’ need to be redone to fit the new game’s visual style, new animations for any new game mechanics are also necessary. This takes less time than doing a whole new model, but it still takes time. If they’re not smart and didn’t do a super-high-res ‘master copy’ to work from and then downscale to different hardware, then… they’re going to have to redo as much stuff as before, such that the work amounts to about the same as doing a wholly new character.
Coding and Bug Testing: Just because the character worked bug-free (or at least “no game-crashing bugs”) in Melee or Brawl is no guarantee they’ll do the same if copy-pasted into Smash 4. There will be a meaningful enough QA process that this new character will require almost as much testing as a wholly new character would.
Balance pass: The devs have to sit down and think about how this character worked in past games and how they want him working in Smash 4. This may involve significant attack redesign (if so, art team has more work to do!). It also requires they discuss it for two different audiences; the general public and elite players. Why would this matter? The best possible example is Ike from Brawl. Elite players think Ike sucks (or at least they did the last time I checked their thoughts, which was a year or more ago I admit), and within their competitive environment he most certainly does. However, the general public thinks Ike is overwhelmingly good and outright call him ‘cheap.’ Why? Because they have no concept of defense and spacing. To them, Ike’s F-Smash is this unavoidable paintbrush of death that covers huge swathes of the arena with each swing… and he’ll kill you as soon as 42% with it. The devs have to be aware of this massive disparity and figure out how to deal with it. This takes up only marginally less time than it does to design up a wholly new character and then have the same balance conversation on that one.
Playtesting: Cyclical with the balance pass above; if an issue shows up in one step they return to the other to get more ideas on how to fix it. If the character has even minor differences from someone else on the roster, this is a significant extra workload. “How?”, one might wonder. Compare Marth and Roy in Melee and you’ll see. Nearly identical in terms of art assets (other than a skin change and a handful of different animations, anyway)… but one turned out to be among the best characters in the game and the other struggled to be relevant just due to a few details being different in their stats/move-list design. Figuring all this out takes time.
Now, what we add this up to is several “saves some time” steps that add up to… well, saving a fair chunk of time. Here’s the thing though; it’s not a non-zero investment, and they must weigh this investment against multiple concerns. Among them:
Customer Satisfaction/Hype-Building: How happy will players be to see this character return? Will it influence sales? Captain Falcon is a “Yes”, Mario is a “Yes”, Marth is a “Yes.” Pichu is a “No.”
What Ends Up Undone?: Think of it as “maximum work able to be done.” Let’s say doing a revised character takes 70 units of work, doing a wholly new character takes 100 (these are purely made up numbers), and the team only has… say, 10,000 Work Units to allocate to the entire project. This is a vast oversimplification, but it’s somewhat apt. While a revised character is more work-efficient, they weigh it against how much extra excitement they can generate if they spend 30% more work to do a wholly new character. Doing the ‘less efficient’ job that pays out more in regard to customer satisfaction (and thus sales) may actually be the smarter choice. Nonetheless, something will go undone and when it comes time to drop projects/ideas… they’ll pick the ones they think the fans will miss the least.
Remember that they can’t half-ass any given aspect of this (serious problems result if they do), and they don’t have unlimited resources. Namco-Bandai and Nintendo are gearing up for their own Q3/Q4 plans and while they might loan the Smash devs an artist for a few days or toss in a few hundred more dollars to cover getting Pat Cashman back in the studio to narrate a few more user interface lines, they’re going to draw the line somewhere and the Smash team will have to make do with what they have. This will inevitably lead to character cuts, such as Roy being removed from Brawl. He wasn’t worth the extra effort since he wasn’t advertising an upcoming game and was not immensely, franchise-definingly popular like Marth was.
This actually lead to a joke in Brawl, back when people were first exploring it. Someone found what they called the “Instant Dash Attack,” which was done by starting a Dash and immediately pressing C-Stick Down (not inward of course, but down). This let you bypass the usual delay on starting such a dash attack had when you input it with Dash plus A, so it was a pretty important thing at the time, and reports came in of “Works for Ike”, “Works for Zelda”, “Metaknight too”, and so on. Then someone playfully posted, “I think I’m doing this wrong; when I try it with Dedede he just falls on his face. Help?”
At any rate… yes, people are seriously overreacting and underthinking if they think that pic confirms Tripping. Why in the hell would Sakurai repeatedly insist it has been removed from Smash 4, only to openly contradict himself all of a week later in a way that would out him as a liar and anger significant numbers of players? I mean… insisting it once would be a translation error (“Wait, the guy rendering English to Japanese for me must have misunderstood, I was not asked the question you think I was, I am very sorry for the confusion”). Insisting it repeatedly across multiple interviews with different publications? Either the translator is making a consistent mistake (possible but unlikely) or Sakurai is telling the truth and tripping is gone and this is just Villager’s dash attack or some other move.
As “Sakurai is telling the truth when he has absolutely no incentive to lie on something that will be easily found and held against him” is the most likely scenario, I choose to believe that.