This was a show which paved way for the likes of Heroes, only - as some have said previously - more original and with better actors (generally speaking, not all of them obviously).
I also have agree with what a reviewer previously said about characters like Tom Baldwin - who was a nancy-pansy most of the time instead of someone with enough of a badass side IMO -, the show's moral compass which was a bit too girly at times and the under usage of the 4400's powers vs. just a slight bit too much talking.
A possible explanation is that it's not like they had a huge budget and were a major top 5 show. They weren't and they had limits.
All in all, they still did a much better show than Heroes with much less dough. It's all about the story and these guys had it.