Well, the user doesn't expect to turn the turret for 90% of the time while taking fire from everything else on the other side.
I think this whole messed up target priorities thing is why I see less and less and less successful T4 land attacks. Although the buildtime thing also helped with that.
Maybe that is also why it seems the Sera T4 bot is used more often... as it's dead weapon doesn't suffer from the same problems, hehe.
I think you're correct - the overly complicated target priorities can cause units to not actually do damage for a long time. As an example, a monkeylord that tries to attack a brick to the south and then a brick to the north while all of the remainder of the army is tech 2. All of the tech 2 will be skipped.
Same why the colossus can no longer walk and fire - it tries to aim at tech 3 units that, by all means, can end up behind him while there are a lot of valid targets in front of him.
Sadly, this is a balance team matter. If it were up to me I'd simplify all the target priorities to 4 - 6 elements, maybe even less in some situations. Allow mods like ATP and the snipe mode to take care of the rest.