Please don't remove UI2: for a lot of people it is still a lot more productive

UI2 has built over time muscle memory, users understand exactly where to go to utilize features and tools. Switching the position, shape or order of tools causes significant churn. 

I have tried UI3 multiple times in the past few months and see major changes being rolled back to where UI2 was initially. I almost always go back to UI2 as its still more functional personally.