The movespeed and movespeed slow soft caps make the game unneccecarily confusing to play
It's very hard to estimate how effective your slows will actually be.
Just to demonstrate: An Udyr is running at your adc with a movespeed of 585. You slow Udyr by 45% in the hopes of saving your adc. How fast does Udyr move? If there were no slow caps you would estimate that he would move at a speed of just over 300 (as his movespeed is nearly 600 and you slow him by nearly half). A movespeed of slightly over 300 would in this case allow you to outrun him. This is not the case however. His new movepseed is actually 390 (33% less than his original movespeed, a whopping 21% faster than expected), allowing him to easily catch up to your adc, and killing both you and your adc, since you had to move in a risky position to slow Udyr.
I don't mind the fact that Udyr can still outrun your adc, but I do mind that this cannot be easily estimated beforehand. I suggest Riot remove the movement speed and movement speed slow caps, and nerf any abilities/items that would be affected by this. I also don't like how this basically makes it so stacking movespeed doesn't really affect your movespeed, but functions more like a quasi-slow resistance (making it pretty much useless to buy multiple movespeed items if your champion already has it in their kit and the enemy team doesnt have large slows (which sounds very specific, but really isn't if you think about it)).
My calculations: https://www.desmos.com/calculator/ghfo3gw7wc Sources: league of legends wikia (for movespeed formula, as well as stats), mobafire (to figure out what runes and items udyrs use for the example).
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