A NOT-NULL column of type TIMESTAMP without a default value in MySQL

If I create a table

CREATE TABLE t1 (
    id BIGINT UNSIGNED NOT NULL,
    createDate TIMESTAMP(3) NOT NULL,
    updateDate TIMESTAMP(3) NULL DEFAULT NULL,
    closeDate TIMESTAMP(3) NULL DEFAULT NULL,
    PRIMARY KEY (id)
)  ENGINE=INNODB;

createDate column is created as

`createDate` timestamp(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP(3),

1) What is the logic behind this? Why MySQL adds the default value? And why it adds ON UPDATE CURRENT_TIMESTAMP(3)?

2) Is it possible to create a column timestamp(3) NOT NULL without the default value?

EDIT1:

I have an impression that id column, for example, does not have a default value, because if I do

insert t1 updateDate values (now());

I get

ERROR 1364 (HY000): Field 'id' doesn't have a default value

so the default value is not added automatically to a column of INT type.