Not really as every little thing has its own reason. Like the merge posts thing mentioned in this topic. We saw tons of user confusion on that so we decided to remove it as it was more trouble than it was worth. Now of course if we find that lessening confusion is not as valuable as people found the feature we could certainly add it back. But that is something we learn with real world use over time
As people start using IPS4 in real use we are certainly open to adding new features or re-adding things that may have been removed or modified from 3.x. I am sure there are things we forgot or good ideas that turned out not so good in real world use. We will certainly evolve the product based on how you use it
If you are using the cron system for rebuilds it should not take weeks. We did out site here in just a few days. You are probably experiencing a bug - please report it to the tracker and we will sort it.