1.One needs brake sensors if one has a throttle, so more to go wrong, also I like to keep my bike as clutter free as possible.
I would not ride an ebike without an ebrake installed, they are trivial to install and can only really go wrong if you don't install them properly (it's simply a hall sensor and magnet).
On my 1500W rear hub (30mph+), I have a PAS independent thumb throttle and the ebrake (left rear), is always on at traffic lights, this ensures that if for example you've left PAS at 5, are at lights and accidentally turn pedal enough to trigger PAS and bike shoots forward...at best you smack in to the vehicle in front of you, at worst you're in to oncoming traffic...
I didn't install the right ebrake as I like to be able to use that brake to slow the bike down a little when I'm in Cruise mode, normally around 22mph, this is optimum for me re comfort and safety and is an absolute pleasure and means I can drive for distance with no messing with throttle, gears or PAS to keep steady speed.
Probably now I would also not ride and ebike that does not have an independent throttle, having that power on tap when driving on major roads gives me peace of mind and on more than one occasion it has gotten me out of potential trouble.