They're just too expensive. Like, sure, it costs money to run, but 3.49€/month (the discounted 24 month rate) for the mail only plan, 15 GB storage. (41.88€, $45.17 USD, $67.28 AUD per year)
That's really expensive if you just want mail.
The other stuff, is also really expensive. To the point that makes you think, "there is no way google is making THIS much to make up the difference in advertising to me for a comparable plan".