Why not take some of that screen space and move the title a bit lower so that it doesn't look so out of place with the whole vertical rythm of the page? The icons to the left are starting at 20px, why not put the title there? The title is also directly linked to those icons. Clicking on an icon changes the title. The title is the current selected icons's title, in fact. Aligning them makes that connection clearer.

That's the kind of questions you should ask yourself when you design an interface.

Right now, the title has a 50px margin because that's the distance the official Slack app uses. However, the official app puts the current user's username there, so that there's Title>10px>Username>30px>Channels ... instead of Title>50px>Channels. It's a direct copy that is missing some elements and that's why it feels wrong to the eye.