That's not how source selection and the contract award process works. Unless the government states in the request for proposal in Section L (specifications) and Section M (evaluation criteria) exactly what will be used for awarding points in a "best value trade-off" competition, there are no points for additional "free" features.
In a cost reimbursable contract (such as JSF), only the features that are included in the government's work breakdown structure (WBS) can be invoiced for payment and those costs for elements in the WBS must be documented according to "cost accounting standards" that are audited by the Defense Contracts Management Agency (DCMA).
If a contractor wanted to put a giant gold winged victory hood ornament on a JSF because he knew that the chair of the source selection committee would love it, they could not invoice for it because it's not in the WBS and it would not pass audit as a G&A.
The source selection committee's rationale for their selection goes through legal review before the award is announced. If the rationale were to say, "lots of cool features that we forgot to list in Section L", the lawyers are going to recommend further evaluation and a better rationale based on Sections L&M because the award would be protested by the losing bidders.
Mission creep is absolutely real, but it's the government that creeps the mission by adding KPPs, KSAs, and ASAs to the spec, not industry throwing in features that the government didn't ask for.
Program Managers trade between cost, schedule, and performance. Getting faster delivery schedule almost always means higher price and lower performance (such as vulnerability to lightning). Conversely, better performance usually means higher cost and slipping the delivery schedule to the right.