3 frames (2 frame buffer) is more than enough time. That's perfectly reasonable and possible to do at high level play.
Actually, since precise timing is really just tech skill....yes they are. Name a single situation where it would be impossible implement rehearsed timing of moves (while actually trying to get the move to come out as fast as possible mind you)
You don't improvise buffer timing. You just press the button
before you can move. Any improvisation in timing is done
after you're already able to move.
No it is not. It's just really hard. At 2 frame buffer (ergo, 3 frame total window)....it's clearly practice.
Have you
ever played melee? Mashing is the least effective way to get these things to come out (mashing causes you to actually
miss the window more often than hitting it). Nobody
mashes those things. The first thing the Marth boards tells people when they ask about double fair is "you're just going to have to practice the timing."
People should not be rewarded for learning their character?

Lag time is a move specific trait that should be learned just like everything else (range, priority, damage, knockback, ect.). Buffering lag is no different than the ridiculous auto aim that's in Halo (where if you shoot
next to the head it hits them anyway)
You
will get the same results. Have you ever played
any other fighter seriously? A 5 frame window is
very generous in most fighters, and you can't seem to handle it? The buffer window is
typically smaller than 5 frames, but no you want 10 frames because you don't want to have to practice, despite the negatives that come with it. A smaller buffer window would easily eliminate these negatives with absolutely no other effect on gameplay (assuming you practiced).
3-5 frames is more than practical. Just FYI, Fox's ledgehop waveland has a smaller window than that. And people do invincible upsmashes because they...practice. Pivot grabs have a smaller window than that (in melee), and every competitive Marth does it now (especially when chaingrabbing).
Actually...yes. The time it takes your brain to register that you've landed the hit (or missed for that matter) and the time it takes you to think of your next move (assuming something didn't go according to plan). The bully would be in "hitstun" (aka...pain).
lol real lif fights.