The skill system is a work in progress. The December build had no level locks and only skill locks (if that).
A large number of RPG's have skills of different power that require you to increase your level before you can use them. I'd go so far as to call it the normal standard.
I do agree with the main thrust of your argument that the system in D:OS isn't working so well. Specifically this (which I have posted elsewhere before):
- You get 3 ability points per level (with an additional point every 5 points into Intelligence).
- The number of ability points it takes to upgrade an ability increases per rank of the ability, from 1 to 5.
- Abilities are capped at 5.
- From hearsay, it seems that the bonuses from Traits, Talents, and equipped items also count towards the cap of 5.
One of my concerns is that it could possibly mean you'll quickly max out your chosen skills by about halfway through the game, and then not really have that much left that you want to put points into.
I also really hate the bonus points counting towards the cap. Bonus points should let you exceed the cap, otherwise they're basically worthless and that encourages you to min-max your character development so you don't waste points. I did not like bonus points from items in Divinity 2 not exceeding the cap either. Having Talent points not exceed the cap is especially bad because a talent is something you are especially good at - better than the average person. If you max out an ability and have a talent point invested to increase that ability, your ability should be greater than someone who maxed out the ability without taking that talent.
I also know that it's not as simple as bumping the cap to 10, either. The amount of points it would take to increase an ability past 5 quickly starts taking several levels to increase just one ability by one rank. In the meantime, you are facing higher level enemies, who because of their higher level, are getting tougher, and your progression could get slow and stagnant, making them harder and harder to deal with.
I agree that the current system of increasing the points requires to learn a new level encourages players into concentrating their points on maxing out their primary abilities immediately and ignoring other ones.