I find it quite ironic that the majority of comments here seem to be against this addition and switching more people to Lyft who haven't already switched for moral reasons. By trying to become a better company and treat drivers better, they scared off the customers who didn't care about that. I'm sure this will get downvoted because I'm implying that people already should have switched for moral reasons, and a lot of people don't care apparently, even when many here can financially afford to pay more.
All of these anti-tipping comments clearly have not used Lyft. The Lyft culture versus Uber's from a passenger perspective is so much better. No, you don't have forced conversations like people here think will happen. People forget that Lyft was originally pushing being the more authentic company from the start. In my experience, the drivers respect this too, and almost every driver I've talked to prefers Lyft riders (even when I'm taking an Uber due to Lyft unavailability).
The tipping option means I can pay my driver more if he helps me unload a bunch of luggage/boxes (I've had to take an Uber to a storage facility years ago and had to use a 3rd party credit swipe app to tip my driver for all the extra work) or some other scenario. There's no tipping mention in Lyft rides, while I've seen it often in Uber rides. It's there for when you need it, and isn't something I really consider much. Is 1 second of thinking really too much? Efficiency isn't that important people.
I agree that tipping ambiguity is a pain sometimes. The remedy is taking the 3-5 min to learn the culture for common tipping scenarios. If you spend that time, the answer is pretty clear here. The feature comes in handy far more than it causes pain, speaking from the epxerience of myself and others.