Ahh, well that will be down to making any decision in Fallout 3 arguably redundant. It's a shame that with the new interactive environment the series is enjoying, it still doesn't feel like a living, breathing world that you as the Lone Wanderer are making any real impact upon. I was disappointed when all the scrap metal I was bringing Walter made no difference, and I realised it was just a never ending cap/exp boost.
To be fair, I didnt see the BOS or Shi running around with Vertibirds after I handed over the plans.
I guess like many things, it was something that the developers chose not to implement, as they'd end up in the situatuon where a) Vegetation started growing at an absurd rate, so much so that folks would here here in the universe thread saying how stupid it was, or b) by putting it on a very long delay, they'd be Implementing content that only a very select few would see.
Personaly I think the oasis situation is possibly Prosecutions witness number 1, as to why Bethesda should have kept with the classic slideshow "Here's what your effect on the wasteland was" ending. I dont know what they were trying to achieve with what they got (especialy as these very boards were full of posts looking forward to such a feature)