Email marketing cheaper is a great attention grabber: kudos for the good copywriting.
Step 1: Link to AWS SES... humm, for that your target audience must be tech-savvy.
Step 2: Query your database... humm, linking my database to a strange system? No freaking way! But assume for an instant that this would be ok. For this, your target audience again must be tech-savvy.
Step 3: Create an email template using MJML... again, for tech-savvy people, not for the average digital marketeer...
Step 4: Review and send... ok, pretty basic..
English -> SQL. Here you got me confused. For steps 1, 2 and 3, your audience must be tech-savvy. This feature doesn't make any sense for tech-savvy people. It only makes sense for the average marketeer in a small team (or solopreneur) who doesn't know SQL. But this guy would never get through steps 1, 2 and 3!
See my point?
A tech-savvy person in a tight budget would develop his own solution. Imho, not your target.
An average digital marketeer or solopreneur who doesn't know how to code and is in a tight budget could be your audience. But for that, steps 1-3 must be no-code/for dummies.
The greatest thing about the idea is "email marketing cheaper".