It's 'simple' because it's so easy to use. Only 3 tabs.
One to see the list of emails requested to bump.
Another to set the bumps (or email sequence).
And the last one, settings such as deciding what day/s and time to send the bumps.

For me, the bumps are just like me sending a personal reminder and stops once the recipient has replied.

So far, based on another account for testing, all my prospects and clients that were rebumped, replied!
Especially all those who haven't been replying the one-off emails.

I've tried cloudhq Follow Up email.
It's a drag to use, is complicated and it doesn't follow up your original email but a preset message.

Lastly, the support has been very helpful.
I messed up on the account and Aaron has been the most helpful and patient.