Info missing: how much time do you have overall for the trip to Monterey, and where on the coast do you intend to resume your originally-planned itinerary? Right now we're being asked if it's worthwhile to spend a couple of hours in the park. You don't say what, if anything, you'd give up to do this. You would be doing a lot of driving over not very scenic territory to see Sequoia/KC. I am referring both to the drive to the parks, and on to the coast (to wherever you are going). http://goo.gl/maps/feFT0
Would I do it? Probably not, since there's so much to see on the coast (e.g., coastal redwoods near Monterey), and I know the scenery along the way to and from the parks is fairly uninteresting. I'd hesitate especially if I had to spend the night in Visalia for such a brief visit (if I could stay inside Sequoia or KC, it'd make a difference, and there is lodging in both). But that's quite another thing from saying it's "delusional," as in it's not possible. It is possible. The decision is yours.
Edited: 4:57 pm, June 22, 2013