IMO, instrumental convergence is a terrible name for an extremely obvious thing.
The actual main issue is that AIs might want things with limited supply and then they would try to get these things which would result in them not going to humanity. E.g., AIs might want all cosmic resources, but we also want this stuff. Maybe this should be called AIs-might-want-limited-stuff-we-want.
(There is something else which is that even if the AI doesn't want limited stuff we want, we might end up in conflict due to failures of information or coordination. E.g., the AI almost entirely just wants to chill out in the desert and build crazy sculptures and it doesn't care about extreme levels of maximization (e.g. it doesn't want to use all resources to gain a higher probability of continuing to build crazy statues). But regardless, the AI decides to try taking over the world because it's worried that humanity would shut it down because it wouldn't have any way of credibly indicating that it just wants to chill out in the desert.)
(More generally, it's plausible that failures of trade/coordination result in a large number of humans dying in conflict with AIs even though both humans and AIs would prefer other approaches. But this isn't entirely obvious and it's plausible we could resolve this with better negotation and precommitments. Of course, this isn't clearly the largest moral imperative from a longtermist perspective.)