How does assigning labors to children, seeing cursed dwarves in the Therapist, mass-designations with quickfort, or the bugfixes/balancing from the Modest Mod not affect gameplay...or improve FPS if you want to ask like that. No one forces you to run embark everywhere... its like dfhack. People want it included, even if you can do things like digv and reveal and killrace with it. Doesnt mean that you have to. I honestly dont see your point. ^^
Very simply it comes down to the following. Adding options a newbie will soon want I'm all for. Think of the options DTherapist gives like seeing cursed dwarves or the balancing/fixes Modest Mod provides.
Turning these things on by default, or "patching" the gamefolder I'm strongly against. If you get into the game as a newbie nothing in my opinion is more frustrating then thinking you're playing Dwarf Fortress and finding out someone decided that they knew what changes there needed to be made to the game for you to easily play it.
I played for a while, tracking down every skulking vampire in my fortress the hard way (checking all relationships with deities), then I got bored doing it, hoped Toady would realise theres a ridiculous amount of vampires in the game and would change it some day, and then I elected to enable the option in DTherapist to show them. I also maybe could've installed a "less vampires mod" but the point is I made the conscious choice to change the way I play the game regarding vampires. If you take this choice for me and just change the game thats fine, but you're no longer just providing helpful tools, you're providing a modded version of the game. As far as I know LNP is not a mod, Accelerated DF is not (supposed to be) a mod, and Accelerated mod is a mod.
There's a list of reason why I think you shouldn't provide newbies with a modded version of a game right of the bat, but I'm sure you can think of most of them yourself. Especially if you ask yourself, would I have wanted Dwarf Fortress to work this way when I first played it.
In the case of DF although I don't like the principle, maybe mod some things right from the start to make it "playable". I don't think thats the things the modest mod includes, even if I think modest mod simply makes DF better. But it is things like accelerated df, fps death should really not exist, graphics tileset, etc. Just things that make the game playable for a newbie. They can always dig deeper ( ;] ) and go ASCII if they want.
tl;dr
When making a newbie pack, give them the option to play DF (almost) vanilla. Then offer them a shitload of options to make the game more enjoyable.
I think we're very much on the same line you even said "Doesnt mean that you have to." The issue really is, when are you telling newbies "Yes, you really have to have this modification"