I am not an EV guy but from a tactical standpoint they can be quieter and I believe they produce a lower infrared signature. Not the end all for every military vehicle but I can see some advantages in some circumstances.

I think the Army's push has more to do with current administrations policies or budget allowances than a drive for trendy/green/electric technology. I feel sure that there is government funds available to the military to switch over to EV and they are taking advantage of that. There is not usually a lot of push to keep the military cool and trendy when it comes down to getting the job done. IMHO

There are lots of places that the military is still using 75+ year old technology because it works. B-52's, 50 cal Browning Machine guns, etc.