- Hamburger menus, like it or not, are widely recognized
- Inertia: everyone else is doing it, so we did it and now it's done (until the next major redesign/funding come along)
- Burgers take up very little space and lend themselves to being tucked into a corner of the screen
- In many instances, they are effective
I want to address that last item in particular. IMO, burger menus are most effective when they contain functions that are less frequently used. Regularly used or core functions of an app or website need to be easily discoverable. Microsoft found this out the hard way with Windows 8, relying too heavily on navigational UI that was revealed only by swiping or mousing from screen edges. To me, an effective solution is to make use of both types of UI tools.
Examples of items that might be included in a burger menu:
- An "About" section...'cause maybe once in a blue moon would one care (We want to buy your company, hire you, compete with you)
- Settings, such as narration, e.g. in some of my apps the user can choose whether to have it and whether the voice is male or female. How often do you need that?
- A contact form (or link to such) or, in the case of an app, a ratings page/control
Examples that would be horrible to include in a burger menu:
- A play/pause button for a video, slide show or timed exercise app
- A send command for a messaging or email app/web page
Non-mobile OSes could place most everything into menus because they have the real estate to display/order things, as well as keyboards (with memorizable shortcuts/commands). Yet think of programs you use, such as Photoshop, Illustrator or Word and how they mix tools/function in palettes with those tucked away in menus.
I hope I answered the original question, but also hope to encourage designers to assess which will be the most effective tools for users, regardless of which way the winds are blowing.