Yeah, no.
I'm not going to start a discussion on that with you until you get that idea out of your head and stop trying to shove your words in my mouth.
Although that is what you did say...
"without a ton of AT's from past games, so that anyone can get up to the point of playing alongside those of higher skill levels with time, rather than after learning a bunch of extra complicated button inputs until they're second-nature."
You see...the place where I have a problem with what you are trying to assert is the bolded and underlined part. First of all the main AT from the first two games wasn't complicated at all. Do an Air move? -> When you land on the ground press L to cancel out some of the air lag. Really wasn't that complicated considering L is used for shielding, used for dodging and so on.
The other one, wavedashing is a combination of something that is pretty simple. 1) short hopping, just press the jump button lightly instead of using up on the control stick to jump. 2) before you get off the ground press L to air dodge and move the control stick towards the ground in the direction you want to move. And this is not that useful on some characters while they can do it. For example I don't see it as that useful on Link since he doesn't go very far and there isn't much more he can accomplish by doing so.
What is the point in gimping any person who does take the time to learn competitive ATs just so people who don't have the will to practice will have a better chance but probably still lose? If you care about winning but don't wish to put in the time and effort other people would put in to learn these techniques to get better. Then you are asking something unreasonable as a pseudo-competitor. I am guessing brawl is your favorite but what is the problem with giving both the competitive and casual side of smash a chance like melee did instead of catering to only one side like Brawl does. And before you say anything, melee was big with competitive but it also had the side of it which was just a bunch of fun. Neither of those playstyles were restricted just because somebody wanted everybody to play the same way by limiting options.
In melee I still have fun with friends playing four player free for all's sometimes with items sometimes not. Sometimes we do bowser challenges for fun (3 player controlled people on the same team no friendly fire, all playing bowser vs one person. It is actually pretty funny.) and sometimes we just do other things that don't have to do with being competitive at all. And don't get me started on when we all just play characters we don't particularly like or play at all, it is a train wreck of just going back to the basics.
I don't often run into people who play melee anymore and aren't competitive (it is a 10+? year old game by now) but if a friend asks for me to stop using wavedashing/L-canceling I will although it doesn't mean their chances of success are better since I have been playing the game for a while now. There is still DI, teching, chain grabs which almost all characters can do, ect ect ect.
Why is it so bad to give the competitive crowd the ability to play how they want to play just like how the casual players have their own way to play? Why force everybody to play one way? There aren't as many of us as you might believe. And SSB4 will be in between melee and brawl anyway so there is no use in hoping that it is Brawl 2.0 or melee 2.0. In the end most casual players will adopt SSB4 as their game, brawl will be left with a very small playerbase, and melee probably won't have any negative effects on it's remaining players. It might get a little bit more interest from being in Evo too.