Can an executive be “forced” to function as a sponsor?

Yes, executives can be and should be forced to function as sponsor, as it is more likely that he/she has good understanding of project sponsors role and responsibility with their work experience, project Management skills and/or some one to guide them with such skills.

Culture shifts within an organization are most successful when driven from the top that is from senior management acting as the sponsors of corporate projects.

To get the full value of project management tools and methodologies, most organizations must undergo a culture shift regarding how they deal with issues such as project prioritization, risk, contingency, communication, and stakeholder involvement.

Is it right for the sponsor to be the ultimate person responsible for the success or failure of the project?

Project success is a team effort, and when the project sponsorship role is better understood, the whole team benefits. But even though it is a team effort, most people working on the project will likely follow the orders, protocols or instructions provided to them. Different teams will follow the plan, schedule and perform job listings as per set of instructions and decision made by sponsor. It is sponsor’s responsibility to provide business context, expertise, and guidance to the project manager and the team, to acts as an escalation point for decisions and issues that are beyond the authority of the project manager; act as the link between the project, the business community, and strategic level decision-making groups.

So, considering all factors above it is better that sponsor to be the ultimate person responsible for the success or failure of the project rather than to hold entire team or department to be accountable for failure.