Alright, I'm going to take a contrary position and argue that a micro-transaction that allowed players to buy skill points to allocate as they please (like when learning and social skill points were refunded) is not a bad thing. I am doing this not because I want CCP to start offering non-vanity purchases in the Noble Exchange but rather to make sure that people don't just have knee jerk reactions to micro transactions and are able to adequately defend their positions.
So our basic assumption is that CCP should not sell anything that gives an in game advantage to player A that player B cannot get through any other means. An example of this would be "gold ammo" with high statistics than regular ammo. Also, "other means" does not include stealing or buying the "gold ammo" from player A.
So selling a paint job for a ship is acceptable, selling Gold Antimatter ammo with better stats than even faction Antimatter is not acceptable.
So skill points. They fall into a grey area that is not as cut and dried as the two examples above. Yes, having more skill points is an advantage but skill points accumulate over time equally for all players. Thus CCP would not be selling an advantage so much as they would be trading time for dollars.
Consider this: you want to fly a Rapier recon cruiser but need Minmatar cruiser V and its 14 days off. Whether you log in constantly for those two weeks or not at all, you will only have access to that skill and thus that ship in two weeks. How unbalancing can it be to allow you to get into that ship two weeks earlier? In other words, the in game advantage player A has over player B is an arbitrary point in time, before which you can't fly a ship and after which you can, regardless of the actions or skills or effort of those respective players.
Look at skill points another way: why does CCP not allow all characters on an account to train skills? Simply put, skill points are doled out at a specific rate to only one character at a time to make you pay more money, either by subbing another account to train a second character or to play your single account longer to do all the training you want to do.
Also, after a certain point (I'll guess 10 million skill points) any in game advantage gained by more skill points is not in terms of making player A superior to player B, its in giving player A more options as to what player B can do. Combat skills, manufacturing skills, trade skills, they all have a certain number of skill points that help them get better and then they cap and the player either puts points into another character or another skill set. A a certain point allowing players to purchase skill points would merely unlock other abilities rather than making them better, abilities that player B could get access to in time regardless of effort (ISK costs for skill books not withstanding since it applies to both parties equally).
Finally, selling skill points would allow CCP to address what is perceived as the biggest knock on the skill point system: that newer players can never catch up to older players. We know that this is mitigated a lot by the aforementioned cap of skill points that any area of skills can accept before being full, but selling skill points might prevent some players from leaving early in frustration.
Of course there would be problems with selling skill points. Make it too cheap and easy and suddenly you find that disposable alts that are extremely useful can be had for the price of a six pack of Coke Zero (aside: so thirsty at the moment). People hunting for kills can never be sure if that 6 month old character is easy pickings or skilled up to the gills by dollars (i.e. birthdate becomes more irrelevant). The rewards of careful planning and neural remapping points becomes virtually moot. And most critically, older players who have lots of skill points by virtue of simply playing the game will complain bitterly and loudly that the game is being "dumbed down" and made "too easy" compared to back in their day.
So, TL;DR verion:
Selling skill points would not violate the "in game advantage" downside of bad micro-transactions and would only allow players more options in a less frustrating manner and faster rate.
OK readers, refute!