I understand totally, because you'd have to add Kalamar, and that's a big headache
That's pretty much it, when I start allowing more it becomes harder for me to draw a line to stop at.
yup, i understand as well. i had this same discussion with a friend and co-player who allows all d20 content in the games he runs. =P i had to explain that i drew my line at whatever wotc says is official which is quite a lot of content when all is said and done. his response seemed to me to be something on the order of 'well, that's kinda silly, but okay if that's what you want'. ^^
he had a hard time understanding why i was being so "limiting & restrictive" when in the past we've gleefully used multiple game systems for our sessions and simply did the math to translate equivalent stats, effects, and damage (we had some pretty epic characters and stories using mix-n-match elements of whatever we wanted from Palladium, TSR, and SJG all in a single concept back in the day)
(and let me tell you from personal experience, taking gurps and rifts element-using characters into d&d yields system
shattering breakage annihilation
apocalypse on a level above and beyond what d&d provides in self-context. you know, reflecting upon it, it was kinda like playing synnibarr when you toss out and reroll any bad rolls. yes, i've actually played synnibarr.)
i confess that i'm not always happy with the amount of stuff that winds up being official and the content is highly variable in quality, but i figured that what the owner says is official was the firmest definition i was going to find. (and recently i've discovered things that should be there, but simply aren't, grrrrr.)