There’s no point doing this to be small. We should go big, if only because there are a lot of people in the world who deserve Slack. Going big also means that it will have to be really, really good. But that’s convenient, since there’s also no point doing it if it is not really, really good. Life is too short to do mediocre work and it is definitely too short to build shitty things.
Putting yourself in the mind of someone who is coming to Slack for the first time — especially a real someone, who is being made to try this thing by their boss, who is already a bit hangry because they didn’t have time for breakfast, and who is anxious about finishing off a project before they take off for the long weekend — putting yourself in their mind means looking at Slack the way you look at some random piece of software in which you have no investment and no special interest. Look at it hard, and find the things that do not work. Be harsh, in the interest of being excellent.
Each of you knows “really good”. Each of you is able to see when things are not done well. Certainly we all complain enough about other people’s software, and we all know how important first impressions are in our own judgements. That is exactly how others will evaluate us.