I'm confused why so many people are complaining about SSB4's speed. Understand that what we have is just a trailer and that there's not enough information just yet to determine competitive capacity. What made Melee feel so rapid, by the way, wasn't natural speed but applied techniques that quickened the game's dynamics (e.g. fast-falling, l-canceling, dash-dancing, wave-dashing, et cetera). For instance, Ganondorf in Melee is naturally slow, clunky, and heavy, but with the applied tactics he can put on quite the show. These techniques--all of which were intended by the developers--were never shown being utilized in any trailers or instructional videos, yet they were always available for the community to access.
The same will be true for SSB4. Sakurai has stated that Brawl was purposefully slown down--both in natural effects and available tactics--to ease Nintendo's expanded audience into the franchise; it's not the same for the next installment, which Sakurai has confirmed to play more quickly than its predecessor. Furthermore, we've already seen fast-falling and dash-dancing (both arguably more vital to the metagame than even wavedashing) in demo videos, so we can be hopeful that Sakurai will retain these tools for competitive use. (Of course, many seen mechanics are still subject to change.)
Moreover, new mechanics will undoubtedly be found and put to use. Just think of all the techniques that allowed Brawl--Brawl, with its tripping and atrocious hit-stun--to play at least somewhat competitively: glide tossing, b-sticking, wave-bouncing, et cetera. SSB4 will most definitely have new tricks to exploit, and I hope that the community is able to focus on exploring the use and application of said tricks rather than complaining about what the game lacks compared to its brother games.
All I'm saying is: quit whining, be patiently optimistic, and focus on what we can do to improve the Smash community.
