Menus are not going to be removed, and Menu Customizer is an enhancement. If you don't like it don't use it. Nobody is being forced to use one over the other. The discussion around removing the Menu management page was from a proposal, which was turned down. I have not yet read a legitimate reason that warrants all this negativity. Menu Customizer is a nice addition to the Customizer, that's all! Please see it for what it actually is, front-end menu management. Why is that such a bad feature to have in WordPress? And before you respond, and yell at me, please think about what I'm saying first. I'm not here to argue about Menu Customizer, just inform people about what it is we're building and that nothing is being replaced or taken away. You're getting more options and the Customizer is being improved in many other ways beyond just Menus. If you find something wrong, please create an issue on Trac. We want Menu Customizer to be the best it can be and address all the functional concerns before 4.3-alpha. Unfortunately, we can't fix your feelings. If you don't like it, that's OK. Just don't use it.