Honestly, I believe a DM should be doing that because that's what the player wants to play. It doesn't matter if it comes from a core or non core or whatever - if the DM's campaign is so inflexible that he won't make room for what a player wants, then I'd have to make a value judgment about that DM. It's the players' campaign too.
Perhaps. And if the campaign was just running a bunch of home-brewed series of adventures, I would agree with you.
But does your answer change if the GM wants to drop $250 bucks on
Rise of the Runelords, with all its associated bells and whistles? And you, as a player, propose to use
Book of Nine Swords,
Tome of Magic,
Spell Compendium and the
Magic Item Compendium, while some other players then ask to play classes and races out of all of the
Complete and
Races of Series?
Because I assure you, in those circumstances, what you propose to do will break the published adventures into a million pieces. Your uber-powered characters will blow through the
Rise of the Runelords, as written. The published Adventure Path just
breaks under the power creep.
The only way that doesn't happen is if the GM wants to then put a
lot of work into beefing up and redesigning the set-piece encounters across all six volumes of
RotRL. (And then ncompensate for addtional XP earned in beefed up encounters, and so on and so forth, with a chain reaction of consequences across six volumes of adventures...)
As it stands, there is already a
LOT of work involved in running and creating other bridge and side material for use during the play of an Adventure Path. Your proposal as a player greatly adds to the GM's burden of running that AP. So much so that I, as a GM, would just outright veto it.
So the "my game too" argument, while true, doesn't really capture the practical problems that such desires really cause. It's not just a matter of "taste, touch and feel".
It's not just a matter of fluff;
it's stone cold crunch we're talking about here.
You can't hand wave this stuff away; it matters.