It is very important for branding and authority. But it is more important for you to have it than your competitors.

If you can get it, then get it. If you can't, then your app or service or offering will need to be amazing to overcome branding, authority and trust issues.

The reason the giants have the .com is because it is necessary to demonstrate authority, longevity and trust.

Good dot com names are also indicative of good business sense. Planning, creative inclination and or the ability to buy a good domain $2000 to $10000 or more say a lot about your business.