Ah you beat me to it, I thought it was about time this topic had it's own thread.
I believe a beginner should start with a good cube for these reasons.
1. A smooth turning cube is easier to turn with your fingers, therefore you can start using 'proper technique' straight away, rather than learning and getting used to wristing, then having to unlearn it later on.
2. A good cube is less likely to lock up, lockups are frustrating, if you are new to cubing you're more likely to have fun, and stick with it, if you're not getting frustrated.
3. Hard to turn cubes are straining on tendons ... 'rubik's wrist' used to be a big thing, but I'm not hearing anyone talking about it now. You are much more prone to RSI and carpel tunnel syndrome from a poorly turning cube. (My personal experience here is that I really got into cubing in the early 2000's, but a month later it had greatly contributed to a crippling RSI that saw me unable to use a computer for a year, and about 7 years before I stopped getting pains. When I started cubing again last year it didn't take long with a storebought before I could start to feel the pains coming back on. But since switching to a F2/A5/Dayan I've never had any hints of pain even after long periods of cubing.
4. Great cubes are cheap, and last a long time, the best cubes cost the same or just a little more than the worst storebought. People who suggest you make a progression: storebought till 1min, then Ghosthand until 40, then F2 till 30, then GuHong, are just recommending people waste money on cubes that they wont get much use out of before having to switch.
---
And here are a few pre-emtive counterarguments:
1. "It's the cuber not the cube." - Yes it's mostly the cuber, but the cube does have a significant effect. There is noway anyone gets the same times on a crappy storebought as they could on a Dayan. People will surely post Felix getting a really fast time on a new storebought, but that's still probably 10% slower than he was on his Haiyan Memory at the time. If anything you'll see the most benefit from a good cube in terms of times earlier on. When I got my first DIY, from the very first solve I went from Averaging 2:30, to 1:15. And just last week after retiring my old GuHong and getting a Lubix ZhanChi my times went from 28s to 25s, pretty much instantly.
2. "I got sub-15 with a storebought." Nobody is saying you 'can't' get good on a storebought (particularly one that you've spent a great deal of time working in), but 'should' you? I'd hazard a guess you could have got quicker faster if you had a good cube from the start.
3. "Your turning accuracy will be better after using storeboughts." Yes, that's true, if you are forced to make each turn accurate to within say 5 degrees, then you'll be more accurate than someone who's used a cube that is tolerant of turns to within 15 degrees. But then since you'll inevitably be eventually moving onto a cube that it makes no noticeable difference if you're 15 degrees out, then does it really matter?
4. "Storeboughts force you to turn slowly, which helps with look ahead.", great... or you could just... I dunno, turn slowly. Slow smooth turning is something most of us will agree is important (sorry Jorghi), which is why we practice it. As eveyone says you have to practice to get better, you have to know what your weak points are and concentrate on them. I think it's not true to say that people will only practice smooth turning if they are 'forced' to by their cube. On the contrary the smoother the cube I find the nicer it is to turn slowly and so the easier it is to concentrate on your look ahead (I've never made so much progress on my F2L as when I got my new ZhanChi, which is just beautiful to turn gently and in a nice smooth flow).
5. "Beginners can't control a fast cube." People say that all the time. Here's what happens, the more you use a stiff cube, the more you rely on faces not turning unless you force them to. When you move to a faster cube you find that you were counting on the cube keeping itself in place, rather than you actually controlling it. Holding the cube properly so that you are in control of it is good technique, and not something you'll learn on a crappy cube. If you give a fast cube to a beginner early (I've done this and seen it with my friends) you get used to it very quickly, and you'll not be learning bad habits.
---
Some of the main reasons people don't want cubers to start with good cubes is, that they themselves either 1. didn't get a good cube until they were pretty fast, and think that what is best for them is best for everyone. 2. can't afford the latest cubes, so argue that people slower than them shouldn't have them either (Do people remember all the vitriol last year when beginners were found to be using Haiyan Memories (then the best cube, but quite expensive) "He shouldn't be using a Memory, he's not even sub-50!" - remember that one kid who was trying to scam/steal his classmate's Memory, because he couldn't afford his own and was much faster/'more deserving of it')
That's all I can think of for now, but I'm sure more will come to me... as I'm sure you'll have noticed this is a subject I get quite passionate about
