although, I would like to clarify that my views are entirely subjective.....
Limited editions, in my view, should be exactly that....
a watch that is a limited number and is not manufactured again.....
Also a limited edition should be really much lower, in numbers manufactured, than the regular edition....
So far, I think that all agree with the above.....
Now, the subjective part...
I will use an example of a watch that I bought, from JLC....
About a year ago, I bought the rg version of the limited edition JLC Amvox 2 DBS....
The DBS edition was supposed to be a limited edition watch and this was supposed to be the only rg....
Apparently, and due, I suppose to the success of the model, JLC made more editions including another rg one...
certainly a bit different, but the same dna and characteristics nether the less.....
I since sold my rg edition and bought a different one- the DBS series is no longer, in my view, a limited edition but
a limited production.......
Don't get me wrong... I love this watch and regard this chrono as truly unique, but I feel that I was mislead....
I would have still bought this one, even if it wasn't a limited edition and probably would have kept the rg....
I consider it bad marketing..... (I can elaborate if you would like me to....)
Now for the AP, the limited editions are really, in my opinion, a regular production watch with different dials...
(I am referring of course to RO & ROO)
There is not much of a difference (apart from the dial of course)....
It is sort of choosing a different colour or options for a car.....
Now , in my opinion again, there is nothing wrong in doing so...
AP, as all other manufacturers are a company and exist to make money, not for charity....
Their policy is right and it is judged by the market...
If they did not sell they would not manufacture them....
Nothing wrong with this....
I just do not like the "limited edition" description....
What Mr Merk should have said, again in my opinion, is that those editions satisfy the existing market....
and AP is going to do so.....
So, to conclude, I have no objection on the different editions but I disagree on the "limited", using the car analogy again....
To further clarify, if I find a "limited edition" AP that I like, I would buy it should my economics permit me ... 
I would be happy to elaborate further if you would like me too...
cheers