Then it's a matter of watching their numbers go down and hitting retreat.
I'm not sure we're playing the same game. I'm trying to keep my units in constant motion. The only units I leave idle are suppression platforms/units (sometimes). I'm constantly moving my orks around and microing individual squads of them (not to mention all the unit abilities I need to activate, disrupt the platform with stikkbombz, stomp here, "aimin' what's dat" on these units, etc).
I will agree that it's not as APM demanding as a "vanilla" RTS, being closer to a RTT game...say World in Conflict, but I disagree on some of the other parts you've mentioned, nor do I positively correlate "high APM" with "fun" or "quality RTS."
If you don't scout your army will get suppressed and destroyed/forced to retreat/faced with a unit you have no counter for. If you do not harass then you will let your opponent get the upper hand. Harassing is very important. If you manage to take a raider group in and kill a squad the enemy may be using to cap then you've given yourself a strategic advantage.
I just really feel like people are downplaying it because it's different than the norm, so they assume that the differences mean it is shallow, which it isn't.
Also, the 5 maps that are in the beta are going to be on the disc. You get two more maps once you install/activate to discourage piracy, and they should be releasing plenty of maps for free over time, since they plan a lot of DLC with the game (maps, probably premium banners/armor appearances, campaigns?). But yeah...too few maps at first, but there will be seven.