Not only is it much cheaper to maintain, but also a lot safer for the work site and workers to maintain as well.

Used motor oil is some nasty stuff, and spilt coolant is quite toxic (but attracts animals).

it is also upgradeable - i.e. an improvement in efficiency for a motor of the same format, or improvements of the battery in the same format can both be "drop in" upgrades. Not necessarily trivial, but much easier than with ICEs.

With all the electronics driving these machines, I don't think they are simpler. There are certainly less moving parts, but if something fails in an electric version you will only be able to debug down to the modular level, which could be VERY expensive to replace. Also, if the manufacture goes bust, you may never be able to get a replacement module so the vehicle is now worthless.