Here's my take on this whole Bidou tech thing.
- Yes I could do a perfect pivot back in order to outspace someone and punish them... Or I could just pivot f-tilt
- I could do a sliding spot dodge in order to dodge someone's attack and punish... Or I could just roll or spot dodge normally.
- I could dash attack out of a crouch... Or I could just down tilt or stand up and then dash attack.
- I could do an edge dash attack but... I can do that already (seriously you just flick the control stick quickly and hit attack after you take your finger off the stick)
- I could instantly wall jump from the ledge and air dodge... Or I could just drop from the ledge and double jump air dodge.
- I could instantly run from my walk... But why? Seriously, what punishes do I miss taking like two frames to run normally?
- I could studder my run without returning my stick to neutral position... Or I could just return my stick to neutral position. Like, that's not even hard lol.
- I could run slower than usual... But again why? It's like walking but without retaining your options.
- Also if you can't RAR normally I really don't know what to tell you.
- I could use Bidou to fast fall while still moving forward... Or I could move my stick down forward and then back forward quickly to keep my momentum. It's not like you need to hold down to fast fall normally.
Many of the cases a player could use Bidou there's a far more simple and just as effective option. That, combined with the fact that you have to make the conscious decision before hand to hold down special in order to use these (thus making it impossible to use spontaneously while still having your special moves available) makes this far too impractical to see widespread use.
The difference between Bidou or perfect pivoting and something like wavedashing is that wavedashing opens up a slew of options that are not only impossible to do without it, but are also distinct and unique in their use from what options are available normally. For example, wavedashing allows me to instantly and without preparation move forward, back, or stop, and use any of my options I'd have while standing out of a dash. That's huge, it basically means I can have the utility of walking and the speed of dashing at the same time. There is nothing else in Melee that allows you to reverse your direction in the middle of your regular dashing animation (not opening dash animation) without stopping.
Perfect pivoting on the other hand, has many of the same effects as wavedashing, but is much more limited because while wavedashing can be done any time you can jump or land, perfect pivoting can only done out of the opening dash animation. This makes a big difference because you can only perfect pivot from very specific states (either standing still or walking) which limits it's utility. You can't perfect pivot out of shield, you can't perfect pivot in the middle of a dash, you can't land with a perfect pivot, you can only perfect pivot when you have the option available to start a dash. This unfortunately means that many of the situations where perfect pivoting would be useful can get the same result accomplished by just moving regularly. Much of these problems are the same ones Bidou has. So while doing optimized perfect pivots across the stage looks cool, there's very little you can do with it that you can't by just walking or dashing normally.
Now this isn't all to say that this is useless, far from it. Perfect pivoting itself does have it's uses, and some characters like Little Mac with things like perfect pivot up tilt gain quite a bit from it. There are definitely advantages to be had with this, but for most characters they're very small ones that are offset by the added complexity and requirement of holding down special. I suggest that players of characters who already benefit more from things like perfect pivoting and dash-trotting like Little Mac, Falcon, and Fox look into this, as those characters will probably gain the most use out of it. For the rest of the cast though, there's more reward on focusing on playing the game solidly than on the tech.