You are not providing any other parameters that's why it does not reboot.
In ansible, you are inputting what state you want to have the machine.
Let's say that you have some running VM with 2GiB of RAM and you want to change it to 4GiB.
If you will start the playbook for the first time it will change to 4GiB and reboot,
but the second time no changes because it already has 4GiB, so no change needed.
The same goes for the boot, I guess the VM already had HD boot and you were trying to change it to it,
ansible checked that it was not necessary.