Eh, it is kind of risky not bottoming out most keys at higher speeds. Piano has more resistance than a red switch, a lot more, and weighs a good deal more. The key operates on a fulcrum, not on a linear axis. Forces required to depress both types of keys and the friction each produces far too different to compare. It is a completely different technique to control depression of red switches (or even blue/brown) than piano keys. You could try to avoid bottoming out your keys, but you may sacrifice some accuracy and consistency to do this. Bottoming out is the way to go on a red switch. The only time I don't bottom out is when streaming much higher BPMs, but I use blue switches. I bottom out 98% of the time, though.
Even this causes inconsistency, because stopping halfway causes the key to behave differently. Hitting a key at rest in the default position is not the same as hitting a key that is coming back up. When you bottom out, you have to bring the key all the way back up with your finger, essentially. This guarantees perfect consistency. It will spring back up at the same speed every single time with the same force if you bottom out. If you stop short, the key will continue down when you lift off, and THEN snap back up. If you are streaming by pressing the key down and letting the key do the rest of the work, you will get inconsistencies. The key will start pressing back on you, which means you have to press the key harder mid stream. This means you have to constantly change the force you press the key with. The more you don't bottom out at high speed, the harder you have to hit the key with your finger. Then you have to deal with your fingers moving faster than the key is moving. A lot of people try to do what would be the intelligent thing by trying to lightly press the keys to avoid bottoming out to go faster (this does sound like the smart thing to do), but osu hates your fingers and intellect and wants you to destroy them. If you do this, you won't be as accurate and consistent, and because of the nature of osu, you have to to be accurate and consistent to play maps well.