Eh? The 'kickdown' position does just this. It gives you a combination of maximum power from the engine and maximum change up speeds from the box. The box is designed to change up at the best possible revs for maximum performance under these conditions. True you could lock the box in any gear and over speed the engine if you wanted to, but that was a pointless operation.
It's true some B-W 35 models didn't allow kickdown to first at speeds well short of the maximum into first, but they all would do auto change ups at maximum power. If yours didn't, the chances are the cable controlling the box was badly adjusted. And since this also controlled the line pressure, the box would wear out quickly due to slipping.
I wish I had a pound for every old Rover P6 or XJ6 I've come across with this cable not correctly set. The vast majority of pro mechanics, let alone DIY owners didn't seem to understand its functions and invariably bodged things. But it was a poor idea - it's much better to use engine vacuum for the main function with a separate kickdown mechanism.
But in any case, this was just a maker using too weak a product for cost reasons. It's not intrinsic in the principle. Although most modern autos have managed to replace some brake bands with clutches. My SD1 with a three speed box has three multi plate clutches and one brake band. The Model 35 you refer to had two of each.
Yes - there's no need for a smooth change on a drill. But what you can't do under power is 'swop cogs' in the old way. You'll break the teeth.