Flexibility can be nice, but it can also get annoying. I don't want to micromanage behavior if the environment can do the right thing for me.
Unrelated, but I also enjoy being able to Ctrl+w,Shift+[hjkl] to move splits around relative to the other splits.
Yeah, but the point is I closed it accidentally. So now I reopen NERDTree or whatever and have to spend a bunch of time micromanaging my splits back into the arrangement I just had them in.
Wasted space sucks, but so does having things wreck my layout in an over-eager attempt to avoid it.