When you're making graphic-intense midlets, it's not so nice that 240x320 devices (5310 XpressMusic, 6500 classic, etc.) have the same heap size as 128x160 devices (3110 classic, 5200, etc.).
It should be common knowledge that a higher resolution also requires more memory.
This in effect also blocks me from caching Canvas-instances, which is correct optimization when you know the user must return to the cached screen.
Instead there's no memory for caching, and all data needs to be loaded again - which might please the network operators, but it's certainly a costly affair for my poor users.