A few years ago you might also ask why would anyone give out $5 certificates? It's not any more work on their part - it's a extra parameter sent to their certificate generator.
Rip-off? Bah! That's nothing compared to Microsoft's SQL Server! With SSL, you have to add the asterisk for more functionality. It takes a bit more work and they charge you 10x the price.
With SQL Server, you can get the Express Edition for $0 or the Enterprise Edition for $thousands. But to build the Enterprise Edition, they actually compile it from the same source code without some #defines that enable various Express Edition data size limits.
They do less work yet charge you infinity times the price. Now that's a ripoff!
Given that almost all clients support SNI (https://en.wikipedia.org/wiki/Server_Name_Indication) nowadays, there's not really a need anymore for wildcard certificates (if all you want to do is enable a few subdomains).
Working at a previous employer a few months ago, their McAfee Web Gateway didn't support SNI either. Sites that depended on it were blocked due to a server name mismatch.
