So just how much needs to change to justify a new version number?! Here's what you have that you didn't before (and likely some more):
- Rewritten to use your graphics processor
- Additional recoding to greatly improve performance on other functions
- Updated import modules allowing use of Collections immediately
- HDR Merge
- Pano Merge
- Facial Recognition
- Background processing on time consuming functions
- Filter Brush for masking with Gradient Tools
- Slideshow improvements
- Pan & Zoom
- Auto Sync to music
- Mobile improvements allowing syncing to all Android devices
What the hell more do you want in order to justify updating version #'s?! You may not use half of it, but that doesn't mean it's not there, significant and useful for others. Heck, what did we get with LR5?! Perspective Correction, Radial Filter, Book Creation stuff. Not much more outside of enhancements to existing functions (don't believe me, watch JKost's video on 10 Hidden Gems in LR5). This is software that's being widely used by all levels of photographers, so did you think they were going to come out with an entirely new interface that was going to require everyone using it to relearn everything? Yeah, that would have sold a lot of copies.