On the flipside it is one of the most annoying to play. You can't mass select units and also units won't auto-engage when attacked. So of you have some tanks guarding a harvester and something with longer range starts plinking them they'll just sit there until they get destroyed. And of course moving those tanks up to engage is maximum micromanagement.
It works ok on smaller scales, but the bigger maps are really annoying to play, especially when you're being harassed by Sardaukar troops.
I loved Dune 2000 when I was a teenager, but I remember never finishing it. The last couple of maps were just too hard for me to beat for all the reasons you listed. I think my sister managed it but it took several goes.
I think you are right. It was called Dune 2. Came on a small number of floppy disks. IIRC it was the first title that Westwood developed, and definitely one of the first RTS games.
It the first PC RTS to gain popularity that is more or less similar to modern RTSs (they all in 1 way or another been inspired by it or its successors). Westwood developed a bunch of titles before it (including some very popular RPGs) but their line of RTS are definitely what they're remembered for today!
It works ok on smaller scales, but the bigger maps are really annoying to play, especially when you're being harassed by Sardaukar troops.