My reading is that Congress has an OBLIGATION to promote the arts and sciences, and has the power to use copyright and patent law to achieve those goals as congress sees fit.
Additionally, even if Congress had an obligation to grant intellectual property rights, couldn't they simply grant patents for a term of 24 hours? or 15 seconds?
From what I've read (c.f. Clinton v. City of New York 1998), Congress can decline to use a power, but it cannot grant that power to another branch of government.
You are literally looking for something that isn't there, because it is not written down.
I would love for a lawyer to chime in, because admittedly this is not my wheelhouse.
If the framers wanted to require that Congress do this stuff, why insert "have the power to" unnecessarily? There's no need for that phrase.
As another point against this being an obligation, if you look at the list of enumerated powers[0], you'll see some that are clearly not obligations. Congress doesn't have to borrow money. They don't have to maintain a navy. They didn't have to establish post offices. They didn't have to create a federal court system. (Granted, it makes a lot of sense for them to do many of these things, but it feels wrong to think that they're required to.)
[0] https://en.wikipedia.org/wiki/Article_One_of_the_United_Stat...
The basic idea here is that an authority (e.g., Congress) that has been given a specific power (e.g., declaring war) is obligated to exercise that power where appropriate.
Do note the specific phrasing above: if there is a situation in which exercising that power is the appropriate course of action, then that power must be exercised. The authority cannot choose not to exercise the power in such a situation.
So, Congress doesn't have to declare war for the sake of declaring war. However, if there is an existential military threat to the USA (e.g., aggression by the Japanese Empire in WW2) you could argue that Congress is obligated to declare war, as this would be an appropriate situation to exercise that power.
Of course, the above explanation is very simplistic. There can be specific wordings that clarify how much discretion that authority has; there may be case law pertinent to that area; and whether a given situation mandates "appropriate" exercise of a given power is never a black-and-white decision.