Reddit AMAs are fascinating in general, but when a Facebook product engineer submits to the free-form Q&A session, it’s right up our alley.

Facebook product engineer Bob Baldwin, who has worked on products like Groups, Events, Photos, and more, took some time to answer some questions yesterday. In that time, he discussed a wide range of Facebook-related topics including Android, Messages, Groups, and even that never-going-to-happen “dislike” button.

Here are some of the best questions and answers from the AMA:

Why did Facebook decide to put time-stamps for when messages are seen?

I didn’t build this feature, but I’m a big fan of it and started working on Messages just after it was introduced. Before read receipts were added, we’d often here from friends and other users that they didn’t feel like the person they were messaging actually got their message. By adding read receipts, it makes messaging through Facebook feel more reliable. It also aimed to decrease the time to it takes for friends to reply, making messages feel more like SMS than email.

Which product are you currently most proud of?

Groups. At launch, it became one of the fastest growing products we’d ever launched, and I was really proud to have worked on it. I think communicating with small groups of people you know in real life is really personal and directed in a way that public sharing cannot match. Over time, I believe more sharing will shift into private sharing (via groups, messages, and other products).

Will Facebook’s Android app ever not suck?

For this question, he referred to mobile guy Joel Seligstein:

Well, we’ve been pretty happy with our trajectory and our last few releases. We’re currently investing a ton in architecture and long-term planning for performance, data usage, stability, and reliability.

He also said…

Next release should have some battery work done in it, and its something we now have a couple people looking into fulltime.

Which product did you build that turned out to be the most difficult and why?

Questions. It was too hard to build a community around this on Facebook, so quality was never that great. It’s also difficult to compare usage of a specialized content type, like questions, to the types of content that can be posted everyday (status updates, photos, etc).

Facebook has done a lot of work making it easy to keep track of events. However, for the average person, they still need to maintain an external calendar (and potentially use some tool to sync Facebook events to it). Are there any plans to add the ability to use Facebook as a full personal calendar?

I don’t think our users currently think of Facebook as the place to store content that isn’t shared in someway, so I think it wouldn’t be used much. Facebook events are primarily about meeting up with friends. Though, I hope our events continue to have better integration with existing calendar systems. iOS integration is really nice, for example.

Will Facebook ever have a dislike button??

Actions on Facebook tend to focus on positive social interactions. Like is the lightest-weight way to express positive sentiment. I don’t think adding a light-weight way to express negative sentiment would be that valuable. I know there are times when it’d make sense, like when a friend is having a rough day, or got into a car accident like my sister yesterday (she’s okay!). For these times, a nice comment from a friend goes a long way.

Speaking of AMAs, Facebook COO Sheryl Sandberg’s name recently popped up on the AMA calendar – but disappeared as of Wednesday morning. We’ ve reaching out to find out what’s going on and will let you know when we hear anything.