Currently the incremental refresh adds new rows but does not alter rows that have changed since the last update. This doesn't work well for many situations where a full refresh is expensive but some of the most recent rows may be altered. I would like to see an option for refreshing altered rows in an incremental extract if there is a Date Modified-type field in the data source.
An example use case is a table in Salesforce or some other cloud-based system that has a million records with some new additions and a small number of changes to existing records each day. You can't do a full refresh very often because of API call limits, but an incremental refresh would leave a number of records outdated. This could make the incremental refresh effectively useless since the data isn't all current. A refresh done as above would solve the issue.