I have no idea how or what your are shooting, but I am sorry to say this, yes for me they are critical on my leupy.
Although I now shoot mostly mil/mil setups (as opposed to the more common and mil reticle/moa turrets, which is incredibly stupid when you think about it. They will be a thing of the past in a few years im sure
but anyway yes, a mil dot is crucial since it allows you to use your scope as an entirely nother instrument, I can now range my target, determine the correct adjustments, calculate holdovers for movement. set up a range card, etc. etc.
there is a trick that allows you to cheat a target reticle into acting in a way that allows it to be used almost the same as if using a mildot called 'the poor mans horse' It is used either when using an older gen 1 mildot or in this case using a target reticle for mil dot ranging, it is also most commonly used when engaging targets at a range that is outside the travel dimensions of your scope generally having to take a close in shot on setup that has say 30-40 mils already built into the rail.
What you basically do is raise your poi to the top of the duplex (assuming there is some type of marking) and then that will then be able to give you a known duplex length to be able to do your calculation for distance, dope etc.