Your arguments are correct, just your example is not - the Imoen related stuff you talk about IS one of those possible sidetracks you talk about, you can CHOOSE or leave aside. I have tried to avoid any of those NEJ traps where you are forced to do something - or game over, The requirements to play her through the game from my point of view are quite reasonable (have her in the party upon the transitions between the various parts, help her solve her quests like she helps you with yours). There are very few timed events by her (and those that are only present you the new quest - you know about it but you can put it to your afenda just as you want). And sure, you can take her into regions of the game I have not considered without problems - only if you want to see the end of her plot you need to follow the main plot roughly through the game (which I think is the BGT concept as such).And what if I want to have the dialogs and see what comes out of it without the enforce rule you BOUND her under ? I could just remove the requirement for her to need to be a mage from the script you bind her under, but I do not want to do it as you could do it for me.
And yes, you are free to tweak any NPC into whatever you want - you will just loose (optional) contents from my mod that was related to that NPC. So I see no real problem in all of that.
It's not an actual optional road if you remove it if I do not fill the requirements for it at the right time. Say take yet another 15th a party member in the party... just think about it. Is there a real need for Imoen to be a mage at all ?... for the conversations to finnish. She too stypid without the class ? ...or not able to understand, while she fills the pre-requirements for it clearly.