This is a config value; if you want more containers per node, use a /23 or a /22 instead. It's entirely up to the operator, there's nothing magical about the default choice of /24 (except for it being easier to perform arithmetic on).

> Thirdly it ties up a huge address ranges with _no_ flexibility.

If you're using 10/8, then you have 16 bits' worth of /24 subnets, so 65k nodes by default. It's true that there are some companies in the world that have to worry about this limit, but for almost everybody I don't think this is a real problem.

But this is the problem that most designs are trying to solve. Large L2s are notoriously fragile. 1,000 nodes, 50-100 pods/node is a lot of ARPs. And sometimes you want partitions between endpoints for security/isolation.

I agree with you about static assignment of addresses. But that's why (most) CNIs work with a controller of some kind for IPAM.

IMO, the problem complexity is hard to compress. You need to distribute/manage MAC addresses, routes, and/or state. Different designs would favor one over another.