I'd like to see in v15:
- Default Gravity Jeep (again)
- Animated GIF prints and decals
- Default Camera Events
- Easy Decal-Making GUI
- A way to add hats and body parts into the player designer, even discount different body parts (no head, no feet, no left hand, etc.)
- Wider range of timescale
- Default server commands to admin or de-admin people
- Support for different languages
- Duplicator, Fill Can, Bot Events, Player Resizing and Transform, Checkpoints, collect items events defaults
- Weapon projectile-changing GUI
- Undo and redo commands for player designer, brick planting and painting, chat
- Support for foreign keyboards
- Customized chat filter (change blacklisted words into custom whitelisted words, different options)
- Farther zoom-in and zoom-out
- Support for tablets
- Optional auto-updater and a "Check for Updates" button
- Easier movie-recording and brick macros
- Higher screen resolution options (widescreen for example)
- In-game forum support
- Skins
- Water FX, Mirror FX, Flash FX and events to rotate FX on a brick
- Auto-contrast (when you look at a bright light other things are darker and vice-versa)
- Lie-down animation with mapped key for players (lie down on your back)
- All-over decals and prints
- Good hover vehicles
- Bouncy ball!
- Private chat
- More transparencies and FX in the player designer
Perhaps v16 will have more of this, it's a lot!