I suppose I'd see the complication as being in terms of too many features being put in version 1.0. Did Maven really need in version 1.0 a repository (with all its configuration management implications), a scripting environment based on Jelly (why choose that?), integration with Gump, project data visualisation, source code metrics?
As for the "big bang", most developers are not seriously going to use Maven until it goes final - all iterations prior to that will be used by a more limited community. The developers will get a lot of useful feedback then which would have been easier to work with if Maven had been a smaller system.
Maybe others see Maven differently. I'm willing to be proved wrong. Only time will tell whether the Maven developers took the right approach.