Like salesforce.com or other cloud service providers, they don't let you host because, having the provider host often delivers faster time to market, allows you to focus on your core competencies / applications, often delivers superior service, and in almost all instances, provides lower total cost of ownership (TCO) compared to premise-based solutions.
For Alinean, the cloud service delivery model provides:
1) a rich on-line / database driven enterprise application, Alinean XcelLive, that would be difficult to manage host on your own - Some of the features include fast tool development, lower cost maintenance, rich customer intelligence, superior access and data security, integrated administration and reporting, and integration with CRM and marketing automation systems. Additional features can be found here: http://www.alinean.com/XcelLive
2) No integration or IT resources needed to initially get the service / tool setup and delivered
3) No need for ongoing IT or webteam costs to manage and maintain - we do it all for you, providing high SLA commitments, application hosting, bandwidth, monitoring, maintenance and technical support - lower total cost of ownership (TCO).
4) Continuous improvement of the application, providing additional features and services over time
5) Ability to not just deliver one tool, but leveraging the cloud platform to deliver an entire suite of marketing and sales tools to help break the status-quo and drive more opportunities and deals.