What are the disadvantages of having electrical conduit penetrate my foundation below-grade?
My house has the main electrical come in below grade (built in 1967 before they knew better).  I would get some small leakage coming in around the conduit where it came through the concrete and later hydro-static pressure pushing water right up into the main breaker box which, though inside, was also below grade.

With a un-floored crawl space, some water leakage is probably not a problem but I'd recommend not taking the risk.  You can paint the conduit to match the house and it'll be basically unnoticeable.  Or plant a bush in front of it.  Or run the wire to the side somewhat and come out of the ground someplace less noticeable.

It's also much easier to run the conduit into the house if you can go through wood framing rather than a concrete foundation.