WIth the CA, you can make the power *decrease* then, if you wish (some of the settings can be made negative for this purpose). I don't know if any built-in controller settings can be changed like this, but the CA can be used between your control system and your controller to do a lot of things that controllers can't do on their own (it's one reason it exists).
That depends on how the specific controlling device works, and the settings chosen in it. In the Cycle Analyst, there are ways to compensate for this, to varying degrees depending on the motor system, situation, and bike gearing, etc.what happens when a hill is encountered? I don't know about others, but I can say that MY cadence is going to slow considerably (no doubt). If we are using cadence to control power, when cadence slows due to an increase in load, power is decreased. When faced with an increased load/hill, decreased power is the LAST thing I would want to see in this situation!
Additionally, if you are riding uphill, etc., you would normally shift down to keep your cadence as close to the same as possible, just like when you ride more slowly, and when riding faster you would shift up to do the same thing. (this is how a regular pedal-only bicycle would be used, too, for those that have never used them). If you don't have continously variable gearing like a Nuvinci, then it's not always exactly the same cadence, but if you have the right gearing setup on the bike it wil be close most of the time. If your gearing range is not wide enough for all the situations you use the bike in, then there will be situations where you can't do this, but if it is correclty geared then you can do so. Many people choose to never shift gears, even when they dont' have motor assist, so they don't realize they can do this, and have to work harder when it's not necessary.
I would love to see the level of control the CA gives you over all of the PAS modes (and throttle modes!) implemented directly in controllers; I don't know of any that do, yet (even the OSFW stuff).
I'd personally like to see it done in a simpler, more user-friendly way, that doesn't require intimate understanding of the interactions between each of the menus and settings, and something that is more graphical in nature, but even if it was done in the exact same way it would still be better than what is presently available in the controllers themselves.
The way I would like to see it done (based on just a minute's pondering) might include something that looks a bit like a graph for the various settings, vaguely like the way the Grin Motor Simulator looks. Set scales for vertical/horizontal view of each of the settings that is proportional to your system's capabilities and the terrain/speeds/etc you have to deal with. Draw (or drag handles on) a line for each of the parameters to set them to how they react for each intersection of these things. If something is out of bounds it just won't let you change it to that, and will alert you (perhaps flashing the line at you from the out of bounds point on, flattening it, etc). If a curve you make for one setting will affect other things, you can see that directly on screen as it changes them, literally as you drag the points of the curve. If you don't like the change, just Undo (infinite levels!) and go back to what you had before you touched it. Save as many presets of these curve sets (or individual curves!) as you like, so you don't have to redraw them for other things, or other setups.
Would be nice if these could be onscreen for the controller itself, but even if they have to be in a setup program on a computer, or tablet/phone app, it would still be a great improvement over what controllers have available now (and even over the CA's present menu system, which could be left intact for those that need access to that).
I'd have to ponder it more to come up with a good GUI for setting this kind of thing up in a way most people could just look at and figure out.