I've been hesitant to weigh in on this debate because I truly am riding the middle ground on my opinion...
For those against the creation of an app, I completely see the point. With many of you coming from SmartThings, I completely agree. The ST apps are crap (classic) and crappier (new). Those who were with ST during the Kickstarter days may remember a lot of what SmartThings took away when they released the current classic app.
I was using IrisV2 until March 2016 when I left for SmartThing due to Iris V2 being a steaming pile of you-know-what at the time. I despise Iris to this day, and have not shed a tear for its' demise.. But, the one thing that I will credit Lowe's for getting right is their app..
For those who never used the Iris app, there are (were) things that you can do in their app that you simply cannot replace with a Hubitat dashboard. The Iris UI was built with the concept of "cards".... It had, for example, a Doors & Windows card that displayed at a glance, on the main page, how many open doors and how many windows were open. How do you replicate that, out of the box in Hubitat?? You can't. In fact, I think you would probably need either complex RM rules, or custom code to achieve.
The same goes for Locks, Smoke devices, garage doors, etc...
How does one view active HSM alarms, triggered devices, and alarm history in the dashboard when .. I don't think you can.. At least I have not figured out how do to that.
Again I am neutral on this because it's been 3 years since I've had a truly usable mobile app.. My intent was to show there are other purposes and use cases for a mobile app that extend beyond what dashboards can currently do.