The GeoEvent product team is currently making a push to review both bugs and enhancements from the product's backlog. Some of these work items are a year or more old and may be partially addressed with changes made for the 10.4.1 release -- which should be publicly available the week of June 1st 2016.
Some changes, particularly those dealing with Field Calculator, Field Mapper, and the handling of date/time values continue to be deferred. The next generation Real-Time event processing, being developed now and scheduled for release December 2016 as an Esri Managed Cloud Services offering, may incorporate some of these long awaited changes with plans to eventually bring them into the on-premises product.
If you have changes you have been looking for, please take a look at the new ArcGIS Ideas space in GeoNet and vote up ideas you want to see implemented. Make sure, if you are submitting a new idea to tag it geoevent to help get it routed to the GeoEvent product team.
Best Regards –