Think that it is ok that jobs loaded to Control-M are at least counted as 1 task. If a job is not needed to be on the plan then why scheduling it?
Further, but this could depend on the contract, i don't think that jobs which are delayed are counted again as a task. To my opinion; any delay of a job already ordered to Control-M should not be counted again for the next day. Please check this with your account manager.
Advantage of tasks is primarily that you pay for the actual usage, maybe easier to plan budget and/or charge back to, if any, actual users of your Control-M environment. Maybe you want to make a split between development and production usage?
And that you can deploy as many agents as you need, without paying additional tier-based licenses.
Hope this supports your decision?