Eventual consistency is definitely weak, but it's useful: if we couple eventual convergence with safety properties, then we can describe non-trivial properties.

The problem, which I alluded to in my first footnote, is that it's hard to guarantee anything stronger than eventual in the presence of partitions. If you want to make sure your system behaves "correctly" under arbitrary partitioning, you necessarily have to admit the trivial cases. What you also want to guarantee is that, in the absence of partitions, the system still "does the right thing"; this often gets lost in the definition of eventually consistent systems, which is why you should consider both safety and liveness.