There are many reasons to buy this.
1) You have idiots for your storage admin and system admin. That no matter how many times a dba tells them exactly how to configure something, they screw it up. This box eliminates the morons. It gives the dba everything under his control.
2) Licensing consolidation. I've seen too many cases of database sprawl at SMB's. For a manager, he knows if it's on this appliance, it's licensed. And if he really needs to he can expand the cores and licensing without have to do another costly (in dba time) hardware migration.
3) Ease of deployment. Having demoed one, it literally only takes a few hours after unboxing to having a database running. There is no way you could setup a two node oracle cluster this fast on a system you build, unless you build 100 of them and get it down to a science.
4) Patching. Firmware and oracle patches are bundled together, supposedly tested and certified to work. Patching is very simplified as well.
5) Disaster recovery. Say you want to setup a D.R. site but don't cannot afford, or convince management, to duplicate your oracle licenses. You can log ship to your mission critical databases on an offsite Database Appliance with limited cores enabled. If you ever DO actually need it in a disaster scenario, you can up your cores and licenses rather fast and you're back in business.
6) Bundled third party software with the database appliance. Vendors have the ability to take a database appliance, put their application on it, and bundle it with the oracle database. Then they can sell an all in one solution with built in high availability and growth potential.
I could go on and on. The only people that fail to see the potential with this device are, frankly, snobs. This device is definitely one of their better offerings. It has the most flexibility and utility of any Oracle product I've seen in a long time.