Depth isn't important, but the point is that that is a cumbersome solution. The point of SS was that all of these different scenarios were solved with one unified method of input, with the goal being to make this as painless, simple, and quick to execute as possible. That just not happening with the "hold ZL and move the analog stick" solution. Because that has to not only be the solution for that particular puzzle, but also every combat situation, and for the poking. It has to feel good, fluid, and easy to do, because that's the entire point of abandoning the motion controls in the first place.

The whole objective of motion controlled sword play is to be able to do all these complex maneuvers with one, easy to execute, method of imput. It's not just directional slashes. What about when you can't lock on but you still need to slash or perform an imput directionally? What about the pierce? What about the Spin Attack? What about the final strike? What about the flip spin, the new maneuver that is besically a virticle spin attack? What about the Skyward Strike? How is that one button input going to handle such a diverse moveset? They can't divide it amungst other buttons because that would take away face button space from other things like items.

How is locking on even going to work if you're holding ZL already for directional inputs? It can't be mapped to both because that causes compatability issues with how the locked-on camera works when you aren't locking onto an enemy. It can't be a separate button because it means an extremely cumbersome button layout when you cant to both lock on and attack directionally.

This isn't a simple issue. There is no way to translate Skyward Sword to a traditional layout in a shippable state without a massively unrealistic remaking of most of the game. If Skyward Sword is ever remastered, the Wii Remote will be the only method of control, like the original.

Any proof that motion controls hurt the game's sales?

Actualy combat in SS is most fun and intresting in any Zelda game.

Also I dont think I could be easy to release a HD port without Motion Controls because whole game is build around it.

Well SS require Motion Plus or Remote Plus, that definitely hurt sales.

I am fine with SS motion controls but Nintendo definitely need to have option for classic controls if they can do that.

About queastion What would have to be changed?

Beside obvious 1080p, new textures and better lighting (I can't imagine how great SS will be looked with this), all kind of warnings and notifications especially when you take rupee for 10th time you will get notification about that same rupee again and again, and again....also Hero Mode from start of game. Fixing this things is very realistic for SS HD.
There are two more things that I didnt like in SS, but those can't be fixed with HD port, terrible backtracking and linearity.

Not happening without motion control. If the NX ditches that, as I think it will, the only remake you'll get is on the Wii U.
Which is very unlikely at this point since we'll have had 3 Zelda games on the console.

That's not true at all. It got 93 on metacritic and its sales were relatively low mostly because it came out so late in the Wii lifecycle.

Yes, direction matters in a lot of cases, except in symmetrical enemy designs like Spemanig's beamos, if an enemy has any sort of defense you must read where and how it's holding it: the simple bokoblins (the regular goblin like enemies), will for example hold it's shield towards the right side for a moment, meaning you have to swing from right to left, because a swing from left to right will be blocked by the shield. They're many in number, and there's other enemies with similar defence tactics too. There's also those where it doesn't really matter: said beamos or the deku babas (the flesh-eating plants) are symmetrical so when they open up their window of attack, only the direction matters. Then there's the enemies that you can just slash anyway you want like bats. It's been about two or three years since I last played it, so don't quote me on this, but I'd say over half the enemies, maybe up to three quarters, uses shield, swords and other defense methods requiring the first method to defeat them.

It's similar with the bosses, though they have dedicated weak spots like eyes, which can just be slashed frantically in any way  when exposed. Ghirahim and the final boss are the exceptions here since they're sword fighters. Ghiraham also fires missiles in a certain pattern that you must counter by striking them with your sword under the same angles.

The bettle works by pointing the remote up or down to move it up or down, and turning your wrist like if you were turning a doorknob, to steer it. Other items require different movements though so controls are different with every item.

Spemanig also mentioned a couple good things. I forgot about the Skyward Strike. It works by holding the remote absolutely vertically (so Link holds the sword up high), then waiting a moment before quickly slashing it down to shoot a sword beam. I guess that could be incorporated into the same stick control I mentioned, but that would probably be a bit clumsy because the stick can't go vertically enough, if you get my drift. Or the spin-attack, which can be performed both vertically and horizontally, is done by holding the remote and the nunchuck side-by-side and swinging them swiftly in the wanted direction.

just do an HD and release it with another motion control

My idea Is that you could use the left analog stick for sword slash example would be a 45 degree down movement on the analog stick would result in a corresponding move with links sword.