So the Eldritch Invocations are one of my favorite aspects of the Warlock class. They give the Warlock a lot of power at different stages, and allow for a lot of customization.
The way for the customization part to stay, is in D&D, the PHB states "Additionally, when you gain a level in this class, you can choose one of the invocations you know and replace it with another invocation that could learn at that level."
That part is important, but does not seem to be implemented in BGIII. Is this a planned change? If not, could this aspect be changed to be more in-line with the rules? This becomes more important in the later levels.
For example, you pick the invocation that gives you mage armor. By level 5 or so, you will probably have better armor, something more enticing will be unlocked, or simply you would like to try out the darkness/devil's sight combo.
Loving the game so far!