Well, setting aside a bit of my sarcasm and snark, having stuff directly implemented is, in general, superior to mods when making considerations for potential for conflicts and ease of installs/movement between PCs (as well as making sure said elements are optimized).
The NPC/Kit mod question is another can of worms entirely, but it kind of breaks down to the "you can read fanfiction for free, so why buy books" or "you can play flash games free, why buy games" lines of reasoning. And, of course, it also falls under the umbrella of additional content integrated into the game. And yes, while stuff from professionals isn't always good and stuff from amateurs isn't always bad, I really can't count more than a handful of truly good mods to BG2 that aren't the general fixpacks.
*shrugs* It is a convenience upgrade (as well as some new features) + content upgrade. It is fine to think it isn't worth the pricetag or the pricetag over your own purchase, but it is somewhat annoying to see that particular brand of snark about it.
All in all, I'm probably more overreacting to a perceived tone than anything.