David Cameron went to Brussels cap in hand to try and renegotiate our terms with them before the referendum and was rebuffed on everything. If anyone truly believed they would suddenly change their tune once we voted to leave and give us everything we wanted on a plate they were kidding themselves.
In fact their hard line tactics probably swayed a few more to want to leave their control. It was clear from that failure by Cameron that cutting all ties would be the only way to truly deliver Brexit.